BIO 120 Midterm III Review

Flashcards for BIO 120 Midterm III Review

What is the name of the enzyme involved in DNA replication?

DNA polymerase

In which direction does DNA polymerase work?

5’ to 3’

What does it mean to say that DNA polymerase does not synthesize de novo?

DNA polymerase does not make a new strand from nothing, only adds nucleotides to an existing strand

Which enzymes open up the DNA?

Helicase, topoisomerase

What is the origin of replication?

Regions of the DNA that open up first (rich in AT)

Which enzyme joins Okazaki fragments together?

Ligase

Which enzyme creates the RNA primer?

Primase

Which enzyme destroys the RNA primer?

RNase

Which proteins prevent single-stranded DNA from coming together during DNA replication?

SSBP (single strand binding proteins)

What exists at the ends of chromosomes to resolve the 'end-replication problem?'

Telomeres - repeat sequences

What is the name of the enzyme that solves the end-replication problem?

Telomerase

What are the parts of a condensed chromosome?

CEN, p-arm, q-arm

What is the diploid number (2n)?

Number of chromosomes in a somatic cell (number of homologous pairs of chromosomes in a somatic cell)

What is the haploid number (n)?

Number of chromosomes in a germ cell (sperm or egg)

What is the difference between germ cells and somatic cells?

Somatic cells - 2n, most cells in the body. Germ cells - sperm or egg - are n (haploid)

What is the difference between homologous pairs and sister chromatids?

Homologous pairs have the same genes in the same order, but genes may be different alleles; sister chromatids are exactly the same chromosome.

What are the different stages of mitosis?

Interphase, prophase, prometaphase, metaphase, anaphase and telophase

What is cytokinesis?

Cell itself divides into two

How is cytokinesis different between animal cells and plant cells?

Animal cells - cleavage furrow; plant cells - cell plate

What are the different stages of the cell cycle?

G1-S-G2-M

What parts of the cell cycle correspond to which stages of mitosis?

Interphase - G1-S-G2; prophase, prometaphase, metaphase, anaphase, telophase - M

What are the important decision points during the cell cycle?

G1 to S - 'restriction point';

What factors does the cell monitor before transitioning past the decision points (G1 to S)?

G1 to S - is the environment favorable? is my DNA okay?

What factors does the cell monitor before transitioning past the decision points? (G2 to M)

G2 to M - has my DNA finished replicating?

What is the difference between sexual and asexual reproduction?

Pass on all your DNA vs pass on half your DNA

What is the life cycle?

Sequence of stages from generation to generation from conception to production of offspring

How does the life cycle differ between animals, plants and fungi?

Animals have a dominant diploid multicellular form; fungi - haploid multicellular; plants - both diploid multicellular and haploid multicellular (alternation of generations)

What is the purpose of meiosis?

Reduce chromosome number from 2n to n

What is the first stage of meiosis that differs between mitosis?

Anaphase I - sister chromatids don’t separate - remain intact as it moves to the poles of the cell

What is independent assortment?

Maternal and paternal sets of chromosomes can assort independently

What is the formula for calculating independent assortment?

2^n = number of possibilities

What is P, F1, F2?

p = parental generation; f1 = first 'filial' ie. second generation; f2 = grandfilial ie. third generation

What are true breeding plants?

Breeding with itself always produces the same phenotype - genotypically homozygous

What is an allele?

Different versions of a gene

What is a locus?

Physical location of a gene

What is a dominant allele?

In the heterozygote, the allele whose phenotype you see

What is a recessive allele?

In the heterozygote, the allele whose phenotype you don’t see

What is Mendel’s law of segregation?

Two alleles for a character separate during gamete formation and end up in different gametes

What does homozygous mean?

Two identical alleles for a particular gene

What does heterozygous mean?

Two different alleles for a particular gene

What is a genotype?

What genes make up an individual - which alleles a particular individual has

What is a phenotype?

Observable physical properties of an organism

What is a testcross?

Individual of unknown genotype - cross it with homozygous recessive

What is Mendel’s law of independent assortment?

Alleles of two or more genes get sorted into gametes independently of one another

What is incomplete dominance?

Recessive allele is nonfunctional - so you see half the effect of the dominant allele

What is codominance?

See both of the alleles in equal amounts