Ch. 19 Intro to Genetics

BIOL 107 Exam 5

What is genetics?

The study of how traits are inherited

How do genes carry instructions?

Through DNA

What do traits in genetics include?

Visible features and internal biological functions

How many genomes to humans have?

About 20,000 genes organizeed into 23 pairs of chromosomes

What is the specific position of where a gene is located called?

Locus on a chromosome

What is a gene?

Segment of DNA that contains coded instructions for building a protein (products help determine oraganisms traits)

How do genes produce proteins?

DNA—→RNA—→AAC—→Protein

What is an allele?

Different version of the same gene (slight differences in DNA sequence)

What is genotype?

Set of alleles an individual carries for a gene

What is phenotype?

Observable trait or chracteristic

What are phenotypes influenced by?

Genotype & Environment

What are alleles called if they are the same?

Homozygous

What are alleles called if they are different?

Heterozygous

What is the principle of segregation?

Allele pairs separate during meiosis I and each gamete receives 1 allele

What are punnett squares?

They help visualize possible genotype outcomes and show expected genotypic and phenotypic ratios

What is the principle of independent assortment?

Genes assort independently and are a result of ranfom orientation of homologous pairs at metaphase I

How do variations arise?

1. Multiple genes

2. Environmental influences

3. Gene interactions

4. Differences in gene expression

What is codominance?

1. Both alleles are expressed equally in heterozygotes

2. Neither allele is dominant or recessive

What is incomplete dominance?

1. Heterozygote has an intermediate phenotype

2. Neither allele fully masks the other

What is pleiotropy?

1. One gene influences multiple traits or systems

2. Common in human biology

What are polygenic traits?

1. Traits controlled by many genes

2. Produces contionous variation

3. (height, skin, eye color)

What is environmental influence?

Gene expression responds to environment (ex: sun exposure—→alters melanin production)

What are multifactorial traits?

Traits influenced by multiple genes and environmental factors (ex: type 2 diabetes or cancer)

Most human traits involve?

Mendel provides the foundation!!

1. Multiple alleles

2. Multiple genes

3. Gene-gene and gene-env interactions