Chapter 2 (Exam 2) Flashcards
Interphase
an extended period between cell divisions, DNA synthesis, and chromosome replication
What phase does the cell grow in and produce the proteins necessary for cell division?
G1
What phase does no cell division take place in?
G0
What is one of the regulated decision point where the cell is committed to dividing?
G1/S phase
What phase does the DNA duplicate in?
S phase
What phase does the cell prepare to divide in?
G2
What can only be passed if DNA is completely replicated and undamaged?
G2/M checkpoint
What two processes occur in the M phase?
mitosis and cytokinesis
Mitosis
seperation of sister chromatids
Cytokinesis
separation of cytoplasm
Prophase
-chromosomes condense
-each chromosome possesses two chromatids
-mitotic spindle forms
Prometaphase
-nucelar membrane disintegrates
-spindle microtubules attach to chromatids
Metaphase
chromosomes line up on the metaphase plate
Anaphase
sister chromatids separate and move toward opposite poles
Telophase
-chromosomes arrive at spindle poles
-nuclear membrane re-dorms and the chromosomes relax
Meiosis
the production og haploid gametes
What phase does DNA synthesis and chromosome replication occur?
Interphase
When does seperation of homologous chromosome pairs, and reduction of the chromosome number by half (also called reduction division)
meiosis I
What occurs in early prophase I?
chromosomes befin to condense and the spindle forms
What occurs in late prophase I?
homologous chromosomes pair; crossing over takes place, and the nuclear membrane breaks down
Synapsis
close pairing of homologous chromosomes in Prophase I
Tetrad
closely associarted four sister chromatids of two homologous chromosomes in Prophase I
Crossing Over
crossing over of chromosome segments from the sister chromatid of one chromosome to the sister chromatid of the other synapse chromosome-exchange of the genetic information; occurs in Prophase I
What phase does random alignment of homologous pairs of chromosomes along the metaphase plate?
Metaphase I
What phase do homologous chromosome pairs separate and randomly distribute chromsomes into the two newly divided cells?
Anaphase I
What phase is the second mechanism of generating genetic variation in the newly formed gametes?
Anaphase I
What phase do chromosomes arrive at the spindle poles and the cytoplasm divides?
Telophase I
What is the final stage of Meiosis I and what occurs in it?
Interkinesis: period of rest that cells enter between meiosis I and II. No DNA replication occurs
When do sister chromatids separate (also known as equatational division)?
Meiosis II
What happens in Prophase II?
the chromosomes recondense
What happens in Metaphase II?
individual chromosomes line up in the equatorial plate
What happens in Anaphase II?
sister chromatids separate and move toward opposite poles
What happens in Telophase II?
chromosomes arrive at the spindle poles and the cytoplasm divides
Kinetochores
-formed on the centromere region of the chromosome
-spindle microtubules attatch to the kinetochore
What is the function of the shugosin protein?
prevents cohesin degradation during meiosis I; protects cohesin at the centromere; eventaully degraded and allows the centromere to break down and the chromatids to seperate
Spermatogenesis
-male gamete production
What is the order of spermatogenesis?
spermatogonium –>Primary Spermatocyte(2n)–>Secondary Spermatocytes (2n)–>Spermatids(1n) –>Sperm
What is oogenesis?
female gamete production
What is the order of oogenesis?
oogonium(2n)–>primary oocyte(2n)–> secondary oocyte (1n) and first polar body–>ovum(1n) and second polar body
Sister Chromatids
held together by cohesin; when cohesin breaks down in mitosis it allows for separation of these
What is the importance of cohesin in chromosomes?
it is key to the chromosomes behavior in mitosis
