Human and applied genetics

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Human and applied genetics
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Section 1 Vocabulary

• 1. Carrier an individual that is heterozygous
  for a recessive disorder
• 2. Pedigree a diagram that traces the
  inheritance of a particular trait through several
  generations using symbols to illustrate the
  inheritance of the trait

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Pedigree Charts Video

• http//www.youtube.com/watch?vPuWhstNgRpkfeature
  youtube_gdata_player

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PEDIGREE CHARTS

• Pedigree charts show a record of the family of an
  individual.
• It can be used to study the transmission of a
  hereditary condition.
• It is particularly useful when there are large
  families and a good family record over several
  generations.

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• You cannot make humans of different types breed
  together so pedigree charts provide one of the
  few ethical ways of studying human genetics.
• Today genetic engineering has new tools to offer
  doctors studying genetic diseases but a genetic
  counselor will still use pedigree charts to help
  determine the distribution of a disease in an
  affected family.

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Symbols used in pedigree charts

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• In a marriage with five children, two daughters
  and three sons. The second son is affected by the
  condition

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Organizing the pedigree chart

• Below is a pedigree chart of a family showing
  four generations. A total of 20 individuals.

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• Generations are identified by Roman numerals.
  Individuals in each generation are identified by
  Arabic numerals numbered from the left. Therefore
  the affected individuals are II3, IV2 and IV3.

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What does this show?
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Examples of traits
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hemophilia
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• Inborn Errors of Metabolism - non-functional
  enzymes              PHENYLKETONURIA -
  PKU     pp                   1/10,000
  births            disfunctional phenylalanine
  hydroxylase               PHE --x--gt  
  PHE-pyruvate    --gt --gt   degraded
  excreted                   accumulates -
  blood/brain barrier mental retardation
•         ALKAPTONURIA         aa       A. Garrod
  in 1908      1/200,000            homogentisic
  acid oxidase --x--gt ALKAPTON  urine oxidizes
  black                    1st suggestion that
  effect of genes was to make proteins             
         and disease is due to a defective
  enzyme/protein.
•         TAY SACHS                tt              
                      1/300,000 births             
  defective lysosomal (gangliosidase) enzyme
  lysosomes swell burst -gt death            Ashkena
  zic Jewish ancestry show   1/ 3,600 births     1
  / 30  is  Tt
•         SICKLE CELL  s            ss      
                        1/6,000 births             
             defective beta polypeptide of
  Hb                        improper folding of Hb
  --gt clogs capillaries                            
       
•  

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• Section 1
• 1. What is the genotype of a person who is a
  carrier for a disease?
• heterozygous

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Cystic Fibrosis

• Cystic fibrosis happens most often in white
  people of northern European ancestry, occurring
  in about 1 out of 3,000 live births.
• In cystic fibrosis, the lungs fill with thick
  mucus a perfect breeding ground for bacteria and
  viruses. Most people with cystic fibrosis have
  almost constant infections in their lungs and
  sinuses.

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• In cystic fibrosis, a defective gene alters a
  protein that regulates the normal movement of
  salt (sodium chloride) in and out of cells. This
  results in thick, sticky secretions in the
  respiratory and digestive tracts, as well as in
  the reproductive system. It also causes increased
  salt in sweat.

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• 2. What ions are to blame for the problem of
  mucus clogging the ducts in people with cystic
  fibrosis? chloride

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Albinism

• Albinism is an inherited condition that is
  present at birth. It is characterized by a lack
  of melanin, the pigment that normally gives color
  to the skin, hair, and eyes. Many types of
  albinism exist, all of which involve lack of
  pigment in varying degrees. The condition, which
  is found in all races, may be accompanied by eye
  problems and may ultimately lead to skin cancer .

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• 3. What is missing in people with albinism?
• Melanin

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Tay Sachs

• Tay-Sachs carriers are found most frequently
  among families of eastern European Jewish descent
  (Ashkenazi Jews). In the United States today,
  approximately one in every 27 Jews is a Tay-Sachs
  carrier.

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What happens if you have Tay-Sachs?

• Children with Tay-Sachs disease lack a vital
  enzyme, hexosaminidase A (Hex-A). Hex-A is needed
  for the body to break down a fatty waste
  substance found in brain cells. Without Hex-A,
  this substance accumulates abnormally and causes
  progressive damage until the nervous system can
  no longer sustain life.
• In its most common variant, known as infantile
  TaySachs disease, it causes a relentless
  deterioration of mental and physical abilities
  that commences around six months of age and
  usually results in death by the age of four

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• 4. What is the effect of Tay-Sachs disease?
• Build up of fats in the brain causing mental
  disfunctions

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• 5. Why are there no cures for these diseases?
• They are all recessive genetic disorders and
  occur due to defects in every cells DNA.

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• 6. If all of the above genetic diseases are
  recessive, then what genotype is necessary to
  have the disorder?
• 7. Are there any disorders that are
  dominant?_________ If so, Name 2
• 8. In a pedigree chart, what symbol represents a
  male? ___________ a female? __________
• 9. What is the purpose of a pedigree chart?
• 10. Draw a pedigree of a boy with galactosemia
  if his father has it, his paternal grandparents
  are phenotypically normal and his mother and
  maternal grandparents are all phenotypically
  normal.

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• 6. If all of the above genetic diseases are
  recessive, then what genotype is necessary to
  have the disorder? Homozygous recessive
• 7. Are there any disorders that are
  dominant?_yes________ If so, Name 2 Huntingtons
  disease and Achondroplasia__
• 8. In a pedigree chart, what symbol represents a
  male? _a square _____ a female? A circle
  __________
• 9. What is the purpose of a pedigree chart? To
  trace the inheritance of a trait over the
  generations and to be able to predict the
  possibilities of the offspring inheriting the
  trait
• 10. Draw a pedigree of a boy with galactosemia
  if his father has it, his paternal grandparents
  are phenotypically normal and his mother and
  maternal grandparents are all phenotypically
  normal.

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Section 2 Vocabulary

• 1. Incomplete dominance
• 2. Codominance
• 3. Multiple alleles
• 4. Epistasis
• 5. Sex chromosome
• 6. Autosome
• 7. Sex-linked trait
• 8. Polygenic trait

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SC.912.L.16.2 Ch 8

• Discuss observed inheritance patterns caused by
  various modes of inheritance, including dominant,
  recessive, codominant, sex-linked, polygenic, and
  multiple alleles.

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Dominant and recessive traits
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Advanced Genetics

• http//www.youtube.com/watch?vYoEgUqHOcbcfeature
  youtube_gdata_player

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1. Incomplete dominance , ( 302 )

• Define (1 pt ) _when the heterozygous genotype
  results in an intermediate between the two
  parents homozygous phenotypes

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Incomplete dominance
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Incomplete dominance

• A mixture of the two phenotypes
• Produces a new
• Phenotype.
• Red X White Pink

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Co dominance

• 2. Codominance 302
• Define (1 pt ) when both alleles are equally
  expressed in the heterozygous condition
• Both are expressed
• Like a dog or cat with
• several colors fur

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Blood groups
A and B are co dominant! This is also an example
of multiple alleles A, B and O
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3. Multiple alleles, ( 304 )

• Define (1 pt ) when a trait is determined by
  more than 2 alleles

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Multiple alleles

• More then two alleles for a trait.
• Blood types A B O
• .

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4. Epistasis , ( 305 )

• Define (1 pt ) when one allele hides or alters
  the effects of another allele.

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• example coat color in dogs 2 sets of alleles E
  determines if the fur is going to be dark. Ee no
  dark pigment, B determines how dar. EEbb Edbb
  will be chocolate brown eebb or eeBb will be
  yellow because e masks the effect of the dominant
  B allele!_

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5. Sex chromosome , ( 305 )

• Define (1 pt ) the one pair of chromosomes that
  determines the sex of the organism. In humans the
  X and the Y.

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6. Autosome, ( 305 )

• Define (1 pt ) All of the chromosomes that are
  not sex chromosomes. These contain the genes for
  everything necessary for life. 22 pair in humans

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7. Sex-linked trait , ( 307 )

• Define (1 pt ) traits controlled by genes on the
  X chromosome.
• Introduction--Sex Linked Inheritance (Video Clip)

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Sex linked traits

• The genes for these traits are on the X
  chromosome, because boys only receive one X
  chromosome they are more likely to inherit
  disorders passed to them from their mother who
  would be a carrier.

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• Color Blindness (Video Clip)

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• Coat color in cats is an X-linked gene, with
  alleles for black and orange-brown, so XBXB and
  XBY cats will have a black coat, while XOXO and
  XOY will have an orange-brown coat. Another
  possible combination for female cats would be
  XBXO. Both of the color alleles would be
  expressed, so the cat would end up being
  partially brown and partially black.

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Q Can a male cat ever be calico?

• A Yes, if hes XXY, which would be abnormal. It
  turns out that abnormal numbers of X chromosomes
  arent as serious as other chromosome number
  abnormalities, because all but one X turn off, so
  an XXX individual would have two Barr bodies, an
  XXY individual would have one, etc.

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• Hemophylia (Video Clip)
• Inherited human traits and patterned sex linked
  inheritance (Video Clip)

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• Organizing information about Sex Linked
  Inheritance in Pedigree charts (Video Clip)

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8. Polygenic trait, ( 309 )

• Define (1 pt ) traits controlled by many genes
  skin tone, height and eye color are examples.

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Height is polygenic
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• 1. Define dominant
• 2. Define recessive
• 3. What is it called when a red flower and a
  white flower are crossed and the result is a pink
  flower results?

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• 4. When the F1 generation of this cross (above)
  is crossed, what do you get for a phenotypic
  ratio? _______________
• 5. What does it mean to be codominant? What is
  an example of co dominance?

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• 6. Why is sickle cell an advantage with regard
  to malaria?
• 7. Human blood groups have several alleles to
  determine the blood type. What is this called?
• 8. What are the alleles for blood type?

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• 9. What happens to the number of possible
  phenotypes when you have multiple alleles?
• 10. What is epistasis?

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• 1. Define dominant The trait that masks the
  trait it is crossed with in the parental cross
  and shows up 100 in the F1 generation.
• 2. Define recessive the trait that is not seen
  when crossed with another in the P cross and does
  not show up again until the F2 generation.
• 3. What is it called when a red flower and a
  white flower are crossed and the result is a pink
  flower results? Incomplete dominance red X
  white Pink

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• 4. When the F1 generation of this cross (above)
  is crossed, what do you get for a phenotypic
  ratio? 121 red pink white
• 5. What does it mean to be codominant? Both
  traits equally show in the phenotype.
• What is an example of co dominance? Blood
  types A and B are co dominant and sickly cell
  trait is co dominant.
• 6. Why is sickle cell an advantage with regard
  to malaria? The sickle cell trait rbcs are
  resistant to the malaria disease_ thus keeping
  this trait around as an advantage.

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• 7. Human blood groups have several alleles to
  determine the blood type. What is this called?
  _multiple alleles
• 8. What are the alleles for blood type? _A_
  ___B_ and O or i
• 9. What happens to the number of possible
  phenotypes when you have multiple alleles? It
  increases the number of possible phenotypes and
  genotypes
• 10. What is epistasis? When one alleles causes
  another to be masked or to not show

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• 11. What is an example of it?
• 12. What are the sex chromosomes? How many are
  there in humans?
• Females have __ males have
• 13. What are the autosomes? How many in humans?
• 14. What are traits on the X chromosome called?

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• 15. Do males or females more often have
  recessive sex-linked disorders? why ?
• 16. Do males or females more often carry the
  disorders? why ?
• 17. What are some examples of sex-linked traits?
  

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• 18. What does polygenic mean?
• 19. What is an example of a polygenic trait?
• 20. Can you usually tell if a trail is polygenic?
  
• 21. Can the environment have an effect on the
  expression of a gene?

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• 11. What is an example of it? _coat color in
  dogs from yellow to black.
• 12. What are the sex chromosomes? Chromosomes
  responsible for determining if an organism is a
  male or a female X or Y How many are there in
  humans? _2 1 pair Females have _XX_ males have
  XY
• 13. What are the autosomes? All chromosomes that
  are not sex chromosomes _How many in humans? 22
  pair or 44
• 14. What are traits on the X chromosome called?
  Sex linked

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• 15. Do males or females more often have
  recessive sex-linked disorders? males_ why ?
  females have a second X with the other gene to
  correct the recessive one males do not!
• 16. Do males or females more often carry the
  disorders? Females why ? they have 2 X
  chromosome , one cn be the recessive while the
  other can be the normal one. They can be
  heterozygous.
• 17. What are some examples of sex-linked traits?
  Red-green colorblindness is an example.
  Hemophilia is another

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• 18. What does polygenic mean? Traits that have
  many genes that cause them.
• 19. What is an example of a polygenic trait? Skin
  color, height, eye color, and fingerprint.
• 20. Can you usually tell if a trail is polygenic?
  When there is a range of phenotypes that forms a
  bell curve
• 21. Can the environment have an effect on the
  expression of a gene? Yes, such as the
  temperature, things people eat, exercise,
  sunlight, genes that are cooler are darker as in
  the Siamese cat and pigment production.

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Section 3 vocabulary

• 1. Karyotype 2. nondisjunction

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karyotype
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Karyotype activity

• http//learn.genetics.utah.edu/content/begin/trait
  s/karyotype/

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Using karyotypes to predict disorders

• http//learn.genetics.utah.edu/content/begin/trait
  s/predictdisorder/

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• Section 3 vocabulary 1. Karyotype 2.
  Nondisjunction
• 1. Where in a Karyotype would you look to see if
  a person would have Downs syndrome?
  __________________________
• 2. What is the usual cause of Downs syndrome?
  __________________________________________________
  _______

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• Section 3 vocabulary 1. Karyotype 2.
  Nondisjunction
• 1. Where in a Karyotype would you look to see if
  a person would have Downs syndrome? At the 21st
  chromosomes, look for an extra chromosome there.
• 2. What is the usual cause of Downs syndrome?
  Non disjunction due to older maternal eggs.

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Summary of genetics video

• http//www.bing.com/videos/search?qgeneticvideos
  viewdetailmidE7AEA272F3FDDB885163E7AEA272F3FDD
  B885163first0FORMLKVR19

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Summary of genetics video

• http//www.bing.com/videos/search?qgeneticvideos
  viewdetailmidE7AEA272F3FDDB885163E7AEA272F3FDD
  B885163first0FORMLKVR19

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• . Do the genetic problems on the web site
  http//biology.clc.uc.edu/Courses/Bio105/geneprob.
  htm for practice with a variety of types of
  problems. Write out your answers to the first 4
  problems as you do them on a sheet of paper.

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Trisomy 21
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Chromosomal Aberrations  -  Mistakes of
Meiosis  

• Aneuploidy - Variation in chromosome    
• monosomy - 1 less than normal                   
                                                    
    
• disomy - normal (diploid)                       
                                                  
• trisomy - 1 more than normal        via   non-di
  sjunction   
• (trisomy 21 - Down Syndrome )

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Alterations of Chromosome Structure         

• breakage of chromosomes can lead to 4 types of
  structural changes                               
                             1) deletions -
  chromosome fragment without centromere is
  lost     cri du chat deletion on chromosome 5
• mental retardation, small head face, cry of a
  cat, fatal               2) duplications - a
  segment is repeated               3) inversions
  - a segment reverses is linear sequence          
       4) translocations - both segments moves form
  one chromosome to another

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amniocentesis
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MUTATIONS

• Any change
• in
• DNA

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Point mutations

• A single base pair is changed.
• THE DOG BIT THE CAT
• THE DOG BIT THE CAR
• Only one letter is different yet.

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Frame shift Mutation

• A single base is added or deleted
• This causes the entire line to be read
  differently!!!
• CCG AAU GGU
• ADD ONE C AND
• CCCGAAUGGU READS
• CCC GAA UGG U

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CHROMOSOMAL MUTATIONS

• Parts of chromosomes break off
• Join to the wrong chromosome
• Chromosomes do not separate correctly during
  meiosis non disjunction

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Trisomy monosomy

• Three where there should be two
• Or
• One where there should be two.

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Class Traits Data Table
Dominant Trait Number of Students Recessive Trait Number ofStudents
Free earlobes Attached earlobes
Hair on finger No hair on finger
Widow's peak No widow's
Curly hair Straight hair
Cleft chin Smooth chin
Smile dimples No smile dimples

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Take a Class Survey

• The traits illustrated above are determined by
  the presence of dominant and recessive alleles.
  Survey the members of your class to complete the
  Class Traits Data Table.

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Results of 1000 students surveyed

• Free earlobes 65.07
• Attached earlobes 34.93
• Hair on fingers 62.29
• No hair on fingers 37.71
• Widow's peak 50.52
• No widow's peak 49.48
• Curly hair 50.24
• Straight hair 49.76
• Cleft chin 47.65
• Smooth chin 52.35
• Smile dimples 62.60
• No smile dimples 37.40

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• answer the following questions.
• 1.Which traits controlled by dominant alleles
  were shown by a majority of students in your
  class? Which were shown by a majority of all
  students?
• 2. Which traits controlled by recessive alleles
  were shown by a majority of students in your
  class? Which were shown by a majority of all
  students?
• 3. Compare your answers to questions 1 and 2. Are
  traits controlled by dominant alleles more common
  than traits controlled by recessive alleles?
• 4. Compare the data for your class with the data
  for all students. How do the percentages
  compare?
• 5. Suggest a hypothesis that might explain any
  large (plus or minus 10) differences found
  between the data for the class and for all
  students.

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BIOETHICS

• 1. What are some of the consequences of using
  selection to create breeds of dogs?
• 2. What are some of the benefits of selecting
  traits in plants or crops?
• 3. What effect might selective breeding of crops
  and animals have on the human population?

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Look at this pedigree
Trait shows in phenotype
1. Is the trait dominant or recessive?
2. How do you know?
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Types of DNA videos

• http//learn.genetics.utah.edu/content/extras/molg
  en/index.html

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Review Questions
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• 1. Where are genes located?
• On a chromosome
• 2. How many alleles does one person have for
  each trait?
• Two
• 3. What is another name for a graphic
  representation of a family tree?
• Pedigree chart
• 4. An example of continuous variation is
• Skin color
• 5. A trait that results from blending two traits
  is called
• Incomplete dominance

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• 6. When two traits both show up in the phenotype
  it is called
• Co dominance
• 7. If a trait is sex linked it usually shows up
  in the
• Male
• 8. Any change in the DNA is called a
• Mutation
• 9. A mutation that changes one nitrogen base
  into another is called
• Substitution/ point mutation
• 10. A mutation that is caused by an additional
  base being added to the code is called
• An addition
• 11. If the base is removed from the code, it is
  called a
• Deletion
• 12. The addition of an extra base causes the
  entire chain of codons to be miss-read, this is
  called a
• Frame-shift mutation

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• 13. When an entire chromosome is added it is
  called
• Trisomy
• 14. When an entire chromosome is missing it is
  called
• Monosomy
• 15. Where is the DNA of a cell located?
• In chromosomes in the nucleus
• 16. What molecule makes a copy of the DNA and
  moves it out into the cytoplasm/
• Messenger RNA /mRNA
• 17. What is the process of copying the DNA into
  RNA called?
• Transcription
• 18. What molecule has an amino acid on one end
  and an anticodon on the other?
• Transfer RNA/ tRNA

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• 19. What does the code in the DNA tell the cell
  how to put together?
• Amino acids to form proteins
• 20. What are the nitrogen bases found in DNA?
• Adenine, guanine, thymine, cytosine
• 21. What base replaces thymine in RNA?
• URACIL
• 22. Is DNA usually a single or double strand?
• Double
• 23. Is RNA usually single or double stranded?
• Single
• 24. What happens in DNA replication?
• DNA unzips and new nucleotides match up to form
  2 strands of DNA from the original one
• 25. How many nitrogen bases are found in a
  codon?
• Three