PT 405 CH4 P2 Genes and Cellular Function

This law allows building of one DNA strand based on the bases in the second strand

law of complimentary base pairing

Describe the 3 steps of DNA replication

1. DNA helicase opens short segment of helix creating a replication fork

2. DNA polymerase assembles new strand of DNA next to one of the old strands - 1 moves away from fork and 1 moves opposite of the other strand

3. DNA ligase puts two DNA strands back together

Since DNA polyermase occasionally make errors, there is 1 error per 1 ___ bases copied

billion

Describe what a mutation is

changes in DNA structure due to replication errors or environmental factors

Describe the 6 steps of the cell cycle

I - G1, S, and G2 collectively

G1 - accumulate materials needed to replicate DNA

S - DNA replication

G2 - replicated centrioles and synthesizes enzymes for division

M - mitosis - nuclear and cytoplasmic division

G0 - cells that have left the cycle, cease to divide

In mitosis, one cells divides into 2 daughter cells with (identical/nonidentical) copies of DNA

identical

List the 4 functions of mitosis

1 embryonic development

2 tissue growth

3 replacement of dead cells

4 repair of injured tissues

Provide an overview of the 4 stages of mitosis

prophase - chromatin turns into sister chromatins and nuclear envelope disintegrates

metaphase - chromosomes line up on the equator

anaphase - chromatids split at centromere and pulled toward opposite poles of the cell

telophase - nuclear envelop forms, chromatids uncoil, and spindles break down

Provide an overview of cytokinesis

cytoplasm divides into 2 cells and interphase begins

Give 5 conditions that cells will divide

1 have enough cytoplasm for 2 daughter cells

2 DNA is replicated

3 adequate nutrients

4 growth factor stimulation

5 open space due to neighboring cell death

Give 2 conditions that cells stop dividing

1 loss of growth factors or nutrients

2 contact inhibition

All humans are __% identical

99.9

There are ___ pairs of homologous chromosomes in somatic cells

- __ autosomes pairs

- __ sex chromosomes pairs

23, 22, 1

Explain the difference between heredity and inheritance

heredity - transmission of genetic characteristics from parent to offspring

inheritance - the passage of hereditary traits from one generation to another

Describe what genetics is

the branch of biology that deals with inheritance

Describe the relationship between locus and alleles

locus - the location of a gene

allele - different form of a gene at the same locus on 2 homologous chromosomes

Describe what genetic counseling is

the area of healthcare that offers advice on genetic problems

Explain the difference between a dominant and recessive allele

dominant - produces protein responsible for visible trait

recessive - expressed only when both alleles are recessive

Explain the difference between genotype and phenotype

genotype - alleles for a particular trait; genetic make up

phenotype - outward expression of genes

Explain the differences between homozygous and heterozygous

homozygous - 2 identical alleles at a particular gene

heterozygous - different alleles for a particular gene

Describe the difference between multiple alleles, polygenic inheritance, and pleiotrophy

multiple alleles - more than 2 alleles for a trait

polygenic inheritance - traits controlled by many genes and has continuous gradations of small differences

pleiotropy - one gene produces multiple phenotypic effects

Explain the difference between codominant and incomplete dominance

codominant - both alleles expressed (red and white flower)

incomplete dominance - phenotype intermediate between traits for each allele (pink flower)

(T/F): In incomplete dominance, neither member of an allelic pair is dominant over the other - resulting phenotype is intermediate

T

Female genotype - __

Male genotype - __

Female - XX

Male - XY

(T/F): Sex chromosomes are only responsible for sexual traits

F; responsible for transmission of several non-sexual traits

Describe what a sex-linked gene is and who it primarily effects

traits that appear on the x chromosome and typically absent on the y chromosome

primarily affect males because there's not counterbalancing dominant genes on y chromosome

(T/F): Dominance and recessiveness of allele determine frequency in a population

F; it does not