Genetics Exam 1

What is genetics?

study of heredity, how inherited variation is encoded, replicated, and expressed and how it evolves over time

What are the three divisions of genetics?

transmission, molecular, population

transmission genetics

field of genetics concerned with heredity and how traits are passed from parent to offspring (classical genetics), focus is the individual organism

molecular genetics

study of chemical nature of genetic information and how it is encoded, replicated, and expressed, focus is the gene

population genetics

study of the genetic composition of populations and how that composition changes geographically and over time, focus is the group of genes in a population

prokaryote genetics

no nucleus, no membrane bound organelles, usually one circular DNA molecule, DNA not complexed with histones in bacteria and some archea, relatively small

eukaryote genetics

membrane bound organelle, does have nucleus, multiple linear DNA molecules (chromosomes), complexed with histones, relatively large

What do you end up with after 1 round of mitosis?

2, 2n (diploid) cells

What does mitosis occur in?

somatic cells

What happens in interphase of mitosis?

doubling of DNA (carbon copies of sister chromatids)

What does G1/S checkpoint do?

maintains cell until necessary enzymes for replication are synthesized

What does G2/M checkpoint do?

detection of DNA damage after replication

What does the spindle-assembly checkpoint do?

ensures that each chromosome is attached to spindle fibers from oppisite poles

What are checkpoints?

transition points during the cell cycle that ensure all cellular components are functioning properly

Sister chromatids vs homologous chromosomes

sister chromatids are 2 identical (usually) chromsomes but in the form of 1 chromosome, they will be split in mitosis, homologous chromosomes are two chromosomes (usually seen with 2 sister chromatids) that have the same genetic material/they have a locus that is the exact same genetic material

What is a product of cell division by mitosis?

two progeny cells with identical chromosomes

When does crossing over occur?

in meiosis (prophase 1), tetrads are formed (homologous chromosome pairs) and they cross over, the site of crossover is called chiasma

What is the difference between metaphase 1 of meiosis and metaphase of mitosis?

metaphase 1 in meiosis, homologous chromosomes pairs are randomly arranged in middle of cell

What happens in anaphase 1 of meiosis?

homologous chromosomes separate, but sister chromatids remain joined at their centromere

When do sister chromatids separate in meiosis?

anaphase 2

How does anaphase 1 differ from anaphase of mitosis?

homologous chromosomes separate in meiosis, whereas sister chromatids separate in mitosis

If a somatic cell contains 2n chromosomes, how many chromosomes and DNA molecules will the first polar body of this sheep have?

n chromosomes and 2n DNA molecules

How many different combinations of chromosomes are possible in gametes of something with n pairs?

2^n, if they have 4 different pairs it would be 2^4 = 16

If a cell has a circulaqr chromosome and histone proteins associated with its DNA, but lacks a nuclear membrane what kind of cell is it and why?

the cell belongs to archaea because it has histone proteins, which are present in archaea and eukaryota but absent in eubacteria

If a cell has a diploid number of 6 before meiosis, how many chromosomes will be in each of the four daughter cells if one pair of chromosomes experiences nondisjunction?

two cells will have 4 chromosomes, and two cells will have 2 chromosomes

compare mitosis and meiosis

during meiosis we produce haploid (n) gametes, so the haploid cells can fuse to become diploid (2n), from fertilized egg you go from 1 cell to many via mitosis

What is the difference between a centromere and a kinetichore?

a centromere is the part of two sister chromatids that meet (usually middle), a kinetichore is a protein structure to help move during mitosis

What is independent assortment?

the fact that in meiosis there are different combinations of chromosomes, it will be 2^n

What is nondisjunction?

a failure of chromosomes to separate properly (in meiosis), results in aneuploidy= condition where a cell has an abnormal number of chromosomes