BIOL 371 Genetics Quiz 1

Mitosis

part of eukaryotic cell division during which the cell nucleus divides into genetically identical cells

Prophase

Chromosomes become visible, nuclear envelop dissolves, spindle forms

Prometaphase

The second stage of mitosis, in which the nuclear envelope fragments and the spindle microtubules attach to the kinetochores of the chromosomes.

Metaphase

phase of mitosis in which the chromosomes line up across the center of the cell.

Anaphase

Phase of mitosis in which the chromosomes separate and move to opposite ends of the cell and then the cell elongates and spindle fibers shorten

Telophase

the final phase of cell division, between anaphase and interphase, in which the chromatids or chromosomes move to opposite ends of the cell and two nuclei are formed.

Cytokenis

the division of the cytoplasm to form two separate daughter cells after mitosis

Centriole

An organelle composed of structures called microtubules which are hallow tubes composed protein and they are present at each pole of the spindle apparatus in animal cells

Centrome

Area where the chromatids of a chromosome are attached

Diploid

(2n) two sets of chromosomes from each parent

haploid

(1n) one set of chromosomes (egg and sperm)

Chromatin

Substance found in eukaryotic chromosomes that consists of DNA tightly coiled around histones

histones

Globular protein that assist in DNA packaging in eukaryotes. Histones form octamers around which DNA is wound to form a nucleosome.

What is the purpose of mitosis

cell regeneration, growth, and asexual reproduction

What types of cells undergo mitosis

somatic or body cells

Crossing over

Process in which homologous chromosomes exchange portions of their chromatids during meiosis.

Synapsis

Pairing of homologous chromosomes during meiosis specifically during prophase 1

Tetrad

structure containing 4 chromatids that forms during meiosis

chiasma

site of crossing over

Gamete

sex cell

Germ cell

immature reproductive cell that gives rise to haploid gametes when it divides

difference between meiosis and mitosis

Meiosis has two rounds of genetic separation and cellular division while mitosis only has one of each. In meiosis homologous chromosomes separate leading to daughter cells that are not genetically identical. In mitosis the daughter cells are identical to the parent as well as to each other.

Which specific cell types undergo meiosis

Sex cells or germ cells

oogonia

diploid ovules that undergoes meiosis to produce oocytes and small polar bodies eventual producing a haploid ovum.

Spermatogonium

A diploid cell that can undergo mitosis to form more spermatogonium, and can also be triggered to undergo meiosis to form sperm.

What are two ways that genetic variation can occur

crossing over and independent assortment

homologous chromosome

chromosomes that have the same length, appearance, and copies of genes, although the alleles may differ

sister chromatids

Identical copies of a chromosome; full sets of these are created during the S subphase of interphase.

Germ plasm theory

cells in the reproductive organs carry a complete set of genetic information that is passed to the egg and sperm

2 basic cell types

Prokaryotic and Eukaryotic

prokaryotes

Cells that do not contain nuclei

Eukaryote

A cell that contains a nucleus and membrane bound organelles

Interphase

an extended period between cell divisions• G1: Cell growth & preparation for DNA replication• S: DNA is replicated• G2: Cell growth & preparation for division

Meiosis I

crossing over, separation of homologous chromosomes, and reduction of the chromosome number by half

Meiosis II

separation of sister chromatids, also known as equational division

Prophase I

The chromosomes condense, and the nuclear envelope breaks down. crossing-over occurs.

Metaphase I

homologous pairs of chromosomes randomly align along the metaphase plate―second mechanism of generating genetics variation in the newly formed gametes

Anaphase I

homologous chromosomes separate, beginning the random distribution of chromosomes into 2 newly divided cells

Telophase I

chromosomes arrive at spindle poles(ends of cell), nuclear membrane reforms, chromosomes loosen up

Prophase II

Chromosomes condense

again, nuclear membrane breaks

down, & centrosomes form the

spindle fibers, which attach to

chromosomes

Metaphase II

Chromosomes line up

in the middle of the cell

Anaphase II

Spindle fibers pull apart sister chromatids toward opposite ends of the cell

Telophase II

Chromosomes are pulled all the way to the ends of the cell, the nuclear membrane re-forms, chromosomes de-condense

how many cells are produced in meiosis

4 haploid cells

how many cells are produced in mitosis

2 diploid cells that are genetically identical. They are clones of the parent cell

why do sister chromatids stay together?

cohesion

Principle of Dominance

The presence of one allele can hide the presence of another allele

Principle of Segregation

Alleles separate from each other when gametes are made

Principle of Independent Assortment

Two different genes separate their alleles independently of one another. This means, for example, that not all yellow peas will also be wrinkled. There can be any random combination of traits. Independent assortment happens in meiosis, both in crossing over in prophase I and in random alignment of chromosomes in metaphase I. When we make a dihybrid Punnett square, we are assuming that independent assortment happened.