2 Genetics

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:

BB

Phenotype


Genotype:

Bb

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

Education

2 Genetics