Genetics

1
Genetics Heredity

• An overview of the history principles of
  genetics

2
Mitosis/Meiosis
Animations

• Living things are composed of cells.
• Cells are specialized and can be grouped into 2
  main groups.
• 1.Somatic cells (body cells)- brain cells, blood
  cells, skin cells, etc.
• 2.Gametes (sex cells) Sperm (male) Egg
  (female).
• Mitosis somatic cell division. A process that
  takes the original cell, copies the genetic
  information and ends up with 2 identical cells.
• Meiosis sex cell division. A process that takes
  the original cell reproduces the genetic
  information and divides twice producing 4 cells
  each with 1\2 the original cells genetic
  information.

3
What is genetics?

• Genetics is the study of how organisms pass on
  information to their offspring
• It also explains characteristics certain
  diseases.

4
What is a trait?

• A trait is a characteristic that is passed on
  from parent to offspring.
• Traits include eye color, hair color, metabolism,
  left or right hand.
• Acquired characteristics like strength
  education are not passed on directly as traits.

5
Who discovered genetics?

• Gregor Mendel was a monk from Austria that is
  called the Father of genetics.
• He worked with pea plants.
• He studied several traits in the peas.
• 1.pod shape
• 2. Pod color
• 3. Seed shape
• 4. Seed coat color
• 5. Plant height
• 6. Flower position
• He was able to predict outcomes noticed
  patterns.

6
Mendels Findings

• He noticed that there were 2 versions of many
  traits.
• He noticed that in certain crosses 1 of the
  traits showed up more than the other.
• He set up experiments to cross plants to see if
  he could predict the traits.
• Mendel crossed plants with different traits to
  create a 2nd generation of plants and all 2nd
  generation plants looked exactly like the parent
  plant with the dominant traits.
• Mendel also crossed 2nd generation plants with
  each other and the recessive trait reappeared
  with a 3-1 dominant to recessive ratio.
• Finally Mendel did a few backcrosses with the 2nd
  generation plants and their parent offspring to
  help predict which traits were dominant
  recessive.

7
Mendels Findings (cont.)

• He called the trait that showed up more a
  dominant trait. The more hidden trait he called a
  recessive trait.
• Dominant trait a trait that seems to hide or
  mask another trait.
• In a cross a dominant trait is shown with a
  capital letter.
• Recessive trait a trait that is masked or
  hidden by a dominant trait.
• A lower case letter in a cross shows a recessive
  trait

8
More of Mendels findings

• There are three possible gene combinations.
• 1. Homozygous (pure) dominant 2 copies of the
  dominant gene.
• 2. Homozygous recessive 2 copies of the
  recessive gene.
• 3. Heterozygous (Hybrid) 1 copy of the dominant
  gene 1 copy of the recessive gene.

9
What is a pedigree?

• A pedigree is a diagram that shows the history of
  a trait in a family.
• They are good indicators that certain traits or
  diseases are possible.
• Males are squares. Females are circles. They are
  usually in order from oldest to youngest from
  left to right.
• Colored parts show the trait being looked at.

This pedigree show 3 generations
10
Punnett squares

• A Punnett square is a method used to predict
  possible gene combinations.
• Dominant genes are given capital letters.
• Recessive genes are given lower case letters.
• Ex Tall (T) is dominant over short (t)
• Possible combinations TT,Tt,tt.

11
Genotype and Phenotype

• Phenotype describes the visible expression of
  genes. (What you see.)
• Genotype - shows the actual gene combinations.
  (What you get).
• Online lab

12
How are traits passed on?

• Traits are passed from parents to offspring.
• They are passed by objects known as chromosomes.
• Chromosomes structures within the nucleus of a
  cell that carry genes.
• Chromosomes occur in pairs.
• Genes are specific locations on chromosomes.
• Organisms receive 1 copy of each gene for a trait
  from each parent.

13
Co dominance and Incomplete Dominance

• Incomplete dominance a situation where an
  organism gets 2 genes that are not dominant over
  each other. Both genes are expressed.
• Ex. Cross a red flower a white flower get a
  pink flower.
• Sickle cell anemia a genetic disease that
  curves red blood cells into a sickle shape. It is
  very painful often deadly. It shows incomplete
  dominance.
• Co-dominance a situation where an organism has
  2 dominant genes both are expressed.
• Ex. Two different colored eyes or alternating
  white red flowers. Also blood types.

Incomplete dominance
Co dominance
Web lab
Blood type game
14
Multiple Alleles/Co dominance and Blood Types

• Multiple alleles - Any of a set of three or more
  alleles, or alternative states of a gene, only
  two of which can be present in a diploid
  organism.
• Eye color, Hair color, blood types are all
  cases of multiple alleles.
• Blood type is also co dominance with A B being
  co dominant and O being recessive.

15
What is DNA?

• DNA stands for Deoxyribonucleic Acid
• It is a long thread like material located in
  the nucleus of cells.
• It has a twisted ladder shape called a double
  helix.
• The shape was discovered by James Watson
  Francis Crick.

16
The Genetic Code

• DNA is made of 4 nitrogen containing base.
• They are adenine,guanine,cytosine, thiamine.
• The sequence of these bases in triplet pairs
  determine an individuals genetic code.
• Example TAG could make left handed, TTG could
  make right handed.

17
Human Genetics

• Humans have 46 chromosomes (23 pairs)
• 1 pair is the sex chromosomes.
• Females have XX
• Males have XY

18
Mutations

• Mutations are changes in the genetic structure.
• They can be DNA mutations or chromosome
  mutations.
• Mutations may be harmful, helpful or neither.

Conjoined twins are caused by a mutation which
wont allow fertilized eggs to split.
19
Gene Mutations
Gene deletion
Gene duplication
Gene inversion
Gene translocation
20
Chromosome Mutations
Trisomy3 copies where 2 should be.
Monosomy 1 copy where 2 should be
21
Genetic diseases

• SICKLE CELL ANEMIA
• TAY SACHS DISEASE
• CYSTIC FIBROSIS
• THALASSEMIA
• DUCHENNE MUSCULAR DYSTROPHY.
• PHENYLKETONURIA (PKU)
• MARFAN SYNDROME
• PROGERIA
• TRISOMY 21 OR DOWN SYNDROME
• SPINA BIFIDA
• ACHONDROPLASIA(DWARFISM)
• HUNTINGTON'S DISEASE

• FRAGILE X SYNDROME
• HEMOPHILIA
• KLINEFELTER SYNDROME
• TURNER SYNDROME
• TRISOMY 18 OR EDWARD SYNDROME
• CRI DU CHAT
• CLEFT LIP/CLEFT PALATE
• TRISOMY 13 OR PATAU SYNDROME
• Blue Rubber Bleb Nevus Syndrome
• Prader-Willi Syndrome
• Waardenburg Syndrome
• Retinoblastoma

22
Genetic Counseling

• If couples have a history of genetic diseases
  they may wish to see a genetic counselor.
• They are specialized doctors who use pedigrees,
  Punnett squares genetic screenings to determine
  probabilities of disorders.
• They then advise the couple of their findings
  their options.

23
Genetic Engineering

• Genetic Engineering involves mapping the genes of
  organisms manipulating them.
• Many of the ideas of genetic engineering are
  controversial because they involve controlling
  traits.
• Cloning, gene splicing, gene therapy are part
  of genetic engineering.

24
Gene Splicing

• Gene splicing involves cutting an undesirable
  gene out of one organism replacing it with a
  desirable gene from another.
• The organisms must be compatible.
• Examples Frost insect resistant plants
  Beefalos.
• A Beefalo is an angus cow that has the size gene
  of the American Bison (Buffalo)

The animal in the front is a normal angus cow.
The animal in the rear is an 8 month old Beefalo.
25
Cloning

• Cloning is the process of using DNA to produce a
  genetic duplicate of an organism.
• Not even identical twins are genetic duplicates.
• Sheep cows have been cloned.
• Human cloning is illegal in the US.

Click and clone mice