GHSGT Review Heredity

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GHSGT ReviewHeredity
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Chromosomes

• What are they?
• Chromosomes are threadlike structures consisting
  of DNA and protein that carry genetic information

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Chromosomes

• How many?
• Humans have 46 individual chromosomes (23 pairs)
• Types
• Chromosomes 1-22 are called autosomes.
• Chromosome pair 23 is the sex chromosomes.

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Chromosomes

• Diploid vs. Haploid
• Diploid the TOTAL number of chromosomes in an
  organism (2n)
• Haploid HALF the total number of chromosomes in
  an organism (n)

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• Location
• Chromosomes are located in the nucleus of a
  eukaryotic cell.
• All cells have the same set of chromosomes.
• Chromosomes are NOT visible until a cell is about
  to divide.

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Why do cells divide?

• Heal wounds
• Grow new body parts
• Replace dying cells
• Produce eggs and sperm

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The M Phase

• Mitosisdivision of the nucleus
• Parent cell and daughter cells are exactly alike
• cytokinesis

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Mitosis vs. Meiosis
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Meiosis

• Specific Differences
• Phases
• Interphase (not a part of meiosis)
• Prophase 1 Crossing-over occurs the pairing of
  homologous chromosomes forms tetrads
• Metaphase 1
• Anaphase 1 centromere does not divide
• Telophase 1 and Cytokinesis

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Meiosis

• Specific Differences cont
• INTERKINESIS not a part of meiosis
• Prophase 2
• Metaphase 2
• Anaphase 2
• Telophase 2 and Cytokinesis

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In animals- meiosis produces haploid reproductive
cells called - gametes
In female animals
In male animals
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DNA

• What is DNA?
• DNA stands for deoxyribonucleic acid. It is our
  genetic code.
• Where is DNA located?
• In prokaryotic cells in cytoplasm
• In eukaryotic cells in the nucleus. It makes
  up the chromosomes.

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What does DNA look like

• Each nucleotide (the building blocks of nucleic
  acids) is made up of
• A sugar (deoxyribose)
• A phosphate group
• A nitrogen base
• DNA is called a double helix. It looks similar
  to a twisted rope ladder.

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Real Picture
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Chargaffs Rules

• Adenine pairs with Thymine.
• Guanine pairs with Cytosine.

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Practice Problem

• Find the complementary strand for the following
  DNA sequence
• ATTGCTCCGTTA

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Protein Synthesis

• Why does our body make proteins?
• Proteins control the rate of chemical reactions
  (enzymes).
• Proteins form bone and muscle.
• Proteins help fight disease.
• Proteins help transport substances into and out
  of cells.

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Protein Synthesis

• Where does protein synthesis take place?
• Protein synthesis takes place in the ribosomes of
  cells.

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Protein Synthesis

• Where is the information for making proteins
  located?
• Information for making proteins is located in the
  DNA.
• To get the instructions from the nucleus to the
  ribosome, another molecule is neededRNA.

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DNA vs. RNA
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Protein Synthesis

• What are the 3 kinds of RNA?
• Messenger RNA mRNA
• Transfer RNA tRNA
• Ribosomal RNA rRNA

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Protein Synthesis

• What are the steps of protein synthesis?
• Transcription conversion of DNA message into RNA
• Translation changing of RNA message
  into protein

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Protein Synthesis

• Practice Problems

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Code Wheel
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Find the mRNA, tRNA and amino acids for the
following

• 1. AAGAGATTGCAG
• 2. GCGAATTTACGC
• 3. ATGGTAATAGCA
• 4. AGTTACCGAGGG

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Answers

• 1. Phe---Ser---Asn---Val
• 2. Arg---Leu---Asn---Ala
• 3. Tyr---His---Tyr---Arg
• 4. Ser---Met---Ala---Pro

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Mutations

• Changes in the DNA sequence (ratcatbat)
• Deletion (rtcatbat)
• Insertion (raatcatbat)
• Substitution (rbtcatbat)

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Punnett SquaresMonohybrid Crosses

• A man who is heterozygous for brown eyes marries
  and has a child with a blue eyed woman. What is
  the chance that the child will have blue eyes?
  Show this cross and give genotypes and phenotypes.

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• A Martian homozygous dominant for blue horns and
  a Martian heterozygous for blue horns mate. What
  is the possibility of producing a Martian with
  red horns?

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• A dad with blue eyes has 6 children with brown
  eyes and one child with blue eyes. His wife has
  brown eyes. What are the genotypes for the
  entire family?

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Sex linked traits

• Sex-Linked Genes
• Genes on the X chromosome
• 100 genetic disorders have been mapped to the X
  chromosome

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Sex-Linked cont

• Sex linked genetic disorders are more common
  among men b/c men only have one X.
• Recessive alleles on the X will be expressed in
  males

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Practice Problems

• A man who is colorblind has a child with a woman
  who is homozygous dominant. What is the chance
  of producing a son who is colorblind?
  Colorblindness is a sex-linked recessive trait.

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Incomplete Dominance

• When one allele is not completely dominant over
  another
• Heterozygous phenotype is somewhere between the
  two homozygous phenotypes

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Incomplete Dominance

The inheritance of curly hair illustrates
incomplete dominance When a curly-haired
individual reproduces with a straight-haired one,
the children all have wavy hair. What offspring
would be produced, in what proportions, when two
people with wavy hair reproduce?
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Codominance

• Both alleles contribute to the phenotype of the
  organism.

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Polygenic traits

• Traits controlled by two or more genes
• Example skin color has 4 different genes

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Pedigree

• pedigree ? chart of a particular phenotypic trait
  across generations
• helps us understand the past and to predict the
  future.
• Since humans have such small numbers of
  offspring, human pedigrees do not show clear
  proportions.

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