2 nd Quarter Biology STAR Review

Meiosis  Production of haploid gametes (sperm and eggs)  Meiosis I  start with a diploid cell  copy DNA  Homologous chromosomes separate  divide to produce 2 haploid cells  Meiosis II  Sister chromatids separate  both haploid cells divide to produce 4 haploid cells

MEIOSIS

Spermatogenesis  production of sperm cells

Oogenesis  production of egg cells

 The formation of a zygote of a normal human male  22 X + 22 Y ----  44 XY  The formation of a zygote a normal human female  22 X + 22 X----  44 XX

Gregor Mendel  Monk in Austria who researched heredity by breeding pea plants

Gregor Mendel  P1 Generation Always pure traits Always pure traits  F1 Generation Always hybrids (mixed traits) Always hybrids (mixed traits)  F2 Generation Always produce a 3:1 ratio Always produce a 3:1 ratio

Gregor Mendel  Trait appearing in the F1 generation is DOMINANT always expressed always expressed  Trait that doesn’t appear in the F1 but does appear in the F2 is the RECESSIVE trait only expressed when there is no dominant allele only expressed when there is no dominant allele

Alleles  Similar traits from different chromosomes are called ALLELES Mom = brown eyes, Dad = blue eyes Mom = brown eyes, Dad = blue eyes  B = brown eyes-dominant  b = blue eyes- recessive  Homozygous – two alleles of a gene are the same (BB, bb)  Heterozygous – two alleles of a gene are different (Bb)

Combining Genes  Genotype – the genetic makeup of an organism (BB, Bb, bb )  Phenotype – the traits that are expressed because of the genotype (Black or brown)

Mendel’s Theories: Law of Segregation  A pair of chromosomes is separated during the formation of gametes

Mendel’s Theories: Law of Independent Assortment Different traits are distributed to gametes randomly Different traits are distributed to gametes randomly Add to genetic diversity Add to genetic diversity

Crossing Over  Results in genetic recombination (new DNA composition)  Add to genetic diversity

Incomplete Dominance  some traits are not completely dominant over others R = red r = white R = red r = white both influence color (Rr = pink) both influence color (Rr = pink)

Codominance  neither is recessive – they both show up Ex. Roan horse color Ex. Roan horse color Ex. Blood types Ex. Blood types

Predicting Results of Genetic Crosses  Punnett Squares Cross rabbits: Brown (bb) × Black (BB) Cross rabbits: Brown (bb) × Black (BB) BbBb BbBb BB b b

Predicting Results of Genetic Crosses  homozygous (BB) × heterozygous (Bb) BBBB BbBb B B B b

Predicting Results of Genetic Crosses  heterozygous (Bb) × heterozygous (Bb) BBBb Bbbb B b B b

DdddDddd Dd d d

Dyhybrid Cross

Production of Gametes:

BbSs X bbSSBSBsbSbs bSBbSSBbSsbbSSbbSs bSBbSSBbSsbbSSbbSs bSBbSSBbSsbbSSbbSs bSBbSSBbSsbbSSbbSs

Structure of DNA  Discovered in the 1950s by Watson and Crick  Double helix– 2 strands twisted around each other each strand is made of linked nucleotides each strand is made of linked nucleotides

Nucleotide  Deoxyribose  Phosphate group  Nitrogen base Adenine Thymine Guanine Cytosine

Replication of DNA Unzip

RNA  Three types of RNA messenger (mRNA) – carries info from DNA to cytoplasm messenger (mRNA) – carries info from DNA to cytoplasm transfer (tRNA) – binds to amino acids transfer (tRNA) – binds to amino acids ribosomal (rRNA) – most common, forms ribosomes ribosomal (rRNA) – most common, forms ribosomes

RNA Uses the following Nitrogenous bases: Uses the following Nitrogenous bases: Uracil Uracil Adenine Adenine Cytosine Cytosine Guanine Guanine

The Central Dogma: The process to create a protein

Transcription: In the nucleus  DNA is copied on mRNA  Remember that RNA uses Uracil instead of Thymine

Translation: Cytoplasm  mRNA moves to a ribosome in the cytoplasm  tRNA helps by bringing amino acids to string together a protein

Transcription or Translation? Polypeptide

Gene Mutations  Substitution GCC/CGA/AUU/GCA Ala/ Arg/ Iso/ Ala GCC/CAA/AUU/GCA Ala/ Glu/ Iso/ Ala Only affects the amino acid containing the substitution

Gene Mutations  Deletion AUU/GCC/CGA/AUU/GCA Iso / Ala / Arg/ Iso/ Ala Iso / Ala / Arg/ Iso/ Ala AUU/_ CCC/GAA/UUG/CA Iso/ Pro/ Glu/ Leu/ Everything after the deletion is wrong

Gene Mutations  Addition GCC/CGA/AUU/GCA Ala/ Arg / Iso / Ala GCC/CGA/AAU/UGC/A Ala / Arg / Asp / Cys / Everything after the addition is wrong

Chromosome Mutations Deletion – loss of a piece of a chromosome because it breaks off Deletion – loss of a piece of a chromosome because it breaks off

Chromosome Mutations Translocation – chromosome breaks and reattaches to a different chromosome Translocation – chromosome breaks and reattaches to a different chromosome

Chromosome Mutations  Nondisjunction Chromosome doesn’t separate properly during meiosis Chromosome doesn’t separate properly during meiosis One gamete gets an extra copy of the chromosome One gamete gets an extra copy of the chromosome Cause of Down Syndrome Cause of Down Syndrome

Chromosome Mutations Trisomy 21 (Down Syndrome) Trisomy 21 (Down Syndrome)

Human Genetics Autosomal Autosomal Males and females inherit the trait equally Males and females inherit the trait equally Sex-linked Sex-linked Males tend to inherit the trait more often because they only have one X chromosome Males tend to inherit the trait more often because they only have one X chromosome Ex. Colorblindness is X-linked Ex. Colorblindness is X-linked

Pedigree Dominant or Recessive? Autosomal or Sex-linked?

Genetic Engineering Recombinant DNA Recombinant DNA DNA made from two or more organisms DNA made from two or more organisms

Genetic Engineering in Agriculture Lots of plants are genetically altered Lots of plants are genetically altered Tomatoes Tomatoes Grapes Grapes Corn Corn Make them more tolerant to drought, different soil types, different climates, and environmental stresses. Make them more tolerant to drought, different soil types, different climates, and environmental stresses.

Genetic Engineering in Agriculture Animal Farming Animal Farming Some dairy cows are given a growth hormone to help them produce more milk Some dairy cows are given a growth hormone to help them produce more milk Other cows and hogs are given growth hormone to make them bigger and fast-growing Other cows and hogs are given growth hormone to make them bigger and fast-growing Some chickens are given growth hormone to make them bigger and lay bigger eggs. Some chickens are given growth hormone to make them bigger and lay bigger eggs.