Lecture 13: Cell Cycle, Mitosis, Meiosis

What is chromatin?

a mixture of DNA, Histones, and other proteins

What are sister chromatids?

duplicated copies of one chromosome and are joined together by a centromere

What are homologous chromosomes?

matching pair of chromosomes you get from each parent

What are the stages of the cell cycle?

G1(GAP 1), S(Synthesis), G2(GAP 2), M(Mitosis)

What occurs in G1 Phase?

first phase of interphase, cell grows bigger, copies of some organelles, makes building blocks for chromosomes to form, build centromeres, and saves energy for replication

What occurs in S Phase?

synthesis of DNA, DNA replication occurs, chromatids from DNA replication attach to centromeres, and duplicates centrosomes

What occurs in G2 Phase?

last phase before mitosis, stores more energy, copies some organelles, makes proteins for chromosome manipulation, cytoskeleton gets dismantled

What occurs in Mitosis?

last phase of cell cycle and has 4 stages (Prophase, metaphase, anaphase, telophase/cytokinesis)

What is interphase?

centrosomes/centrioles are present and will spit out spindle fibers, Chromatin is loose, nuclear envelope is intact, and the cell will spend 90% of its life in this phase

What is prophase?

centrosomes/centrioles move toward the pole of cells, spindle fibers form, chromatin condenses into chromosomes, and nuclear envelope starts to break down

What is Metaphase?

Centrosomes are at the poles and spindle fibers attach to centromeres and push chromosomes to the metaphase plate

What is Anaphase?

spindle fibers pull sister chromatids apart towards separate poles and sister chromatids now referred to as daughter chromosomes

What is Telophase?

cell begins to divide, centrosomes split up, chromatin relaxes, nuclear enevlope reforms

What is Cytokinesis?

when the daughter cells actually split

What is the difference between haploid and diploid?

haploid are just the gametes(sperm/eggs) while diploid are zygotes

What is the purpose of mitosis?

is how somatic cells divide and is regular everyday cell division. The result of mitosis is 2 identical daughter cells

When does meiosis occur?

occurs between G2 and M of the cell cycle

What is the difference between somatic cells and gametes?

somatic cells are 2 identical diploid cells while gametes are 4 non identical haploid cells

What occurs in Prophase I?

centrosomes/centrioles move toward the pole of cells, spindle fibers form, chromatin condenses into chromosomes, and nuclear envelope starts to break down. Homologs undergo synapsis which forms tetrads, crossing over occurs, and homologs may swap some alleles with one another

What occurs in Metaphase I?

tetrads line up at metaphase plate, spindle microtubules attach to kinetochore of each chromosome, and where independent assortment occurs

What occurs in Anaphase I?

chromosomes pulled to opposite sides by spindle fibers from centrioles and recombined homologs

What occurs in Telophase I?

chromosomes move towards poles, cell begin to divide, 2 non identical haploid cells form

What occurs in Prophase II?

nuclear envelope breaks down, new spindle fibers form, and centrosomes move to poles

What occurs in Metaphase II?

chromosomes line up at metaphase plate, spindle fibers attach at kinetochore, and chromosomes will form a single file line

What occurs in Anaphase II?

spindle fibers pull sister chromatids to opposite poles

What occurs in Telophase II?

distinct nuclei form at opposite poles, cell begin to divide, and end up with 4 haploid non identical cells

What is the nuclear envelope?

surrounds and protects the nucleus

What are centrioles?

organelles in animals that spit out and organize in spindle fibers. NOT FOUND IN PLANTS

What is centrosomes?

the region of the cytoplasm where centrioles are found

What are homologs?

an alternative name for homologous chromosomes

What is synapsis?

process of homologs pairing up

What are tetrads?

set of 4 chromatids

What is crossing over?

when homologs might swap some alleles with one another

What is the metaphase plate?

the equator of cell during mitosis or meiosis I or II

What is centromere?

it is what connects homologs together

What is independent assortment?

where genes are randomly assorted into gametes

What are kinetochore?

proteins in the centromere