Date post: | 13-Apr-2017 |
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Geneticsand Heredity
Genetics and Evolution
Evolution = change in gene frequencies within populations over time.
Cell Diagram
DNA (deoxyriboneucleic acid)
Protein Synthesis
• DNA is a molecule that provides the cell instructions on how to create proteins.
• Protein Synthesis refers to the construction of proteins from the DNA sequence
Proteins
• Proteins are large organic compounds composed of amino acids.
• Most enzymes are proteins. Many hormones are also proteins.
The DNA Code
• Four Bases: Adenine Thymine Guanine Cytosine
• A T C G A T T A T C G C G • T A G C T A A T A G C G C
Protein Synthesis
• From the DNA sequence our bodies builds proteins. Each three bases represents an amino acid. So the sequence of DNA determines what sort of protein will be produced.
DNA and Genes
• A gene is a unit of DNA that codes for one protein.
• A gene is located at particular region or locus of a particular chromosome.
DNA, Genes and Chromosomes
Long strands of DNA (containing many genes) are wound up into structures called chromosomes.
Chromosomes
• Humans have 23 pairs of chromosomes (46 total).
• 22 pairs of autosomes.
• 1 pair of sex chromosomes.
Sex Chromosomes
XX = Female (two copies of the same chromosome)
XY= Male (two different chromosomes)
Chromosomes
Meiosis and Mitosis
• Mitosis = cellular division resulting in new cells with the same number of chromosomes as their “parents.”
• Meiosis = cellular division resulting in cells with HALF the number of chromosomes as our body cells (sperm & ova).
Mutation
• Random changes in genetic material occur all the time. We refer to these as mutations.
• Mutations are responsible for the genetic variation we see within a population of organisms.
Alleles
• Allele: a variation of a particular gene.
Genes and Inheritance
In most circumstances, we inherit two copies of each gene (allele): one from each parent.
Genotype vs. Phenotype
• Genotype = the genes you’ve inherited from your parents
• Phenotype = a particular observable trait (blood type, hair color…etc.).
Genes and Inheritance
• Alleles (gene variants) can be said to be dominant or recessive in relationship to each other.
• Dominant alleles can “hide” or “cover up” the expression of recessive alleles.
Heterozygous vs. Homozygous
• Heterozygous: having two different alleles. (A and a)
• Homozygous: having two of the same alleles (A and A)
Eye Color: an Exercise
• The Eye-Color gene has two alleles:
• B (brown) is dominant• b (blue) is recessive
Genotype vs. Phenotype
Genotype:
BB
Phenotype
Genotype vs. Phenotype
Genotype:
Bb
Phenotype
Genotype vs. Phenotype
Genotype:
bb
Phenotype
Eye Color Exercise
Mother Father Bb X bb Child B b Bb
Punnett Square
Incomplete Domination
• The Petal color gene has two alleles: R (red) and W (white)
Genotype PhenotypeRR RedWW WhiteRW Pink
Blood Groups
Blood Type
• Three alleles: A, B & O• A is dominant to O• B is dominant to O• A and B are co-dominant
Possible Genotypes: AO, AA, BO, BB, OO, AB
Monogenic vs. Polygenic
• Monogenic = one gene
• Polygenic = multiple genes
Gene to Trait
Genotype +
Environmental Influences=
Phenotype