Download BIO 101 Exam #2 Study Guide

BIO 101 – Exam #2 Study Guide
Chromatin – strands of DNA in nucleus during Interphase
Sister chromatids = two half’s of a chromosome
Chromatids = 2x # of chromosomes / one half of a replicated chromosome
Chromosome = coiled up DNA that passes genes on the DNA to daughter cells when the cell divides
a. most visible during mitosis/meiosis
5) Centromere – middle of a sister chromatid
i. Divides at onset of Anaphase in Mitosis and Anaphase II in Meiosis
6) Spindle fibers – what pull chromosomes apart during cell division
7) Cleavage furrow – bit of cleavage that animal cells make when dividing
8) Diploid (2n) – cell containing 2 homologous sets of chromosomes, one from each parent
i. Reproduces sexually
ii. What all cells have except egg + sperm
iii. Double the haploid
9) Haploid (n) – half the Diploid # of genes, is the egg + sperm cells
10) Dyad = 2 chromatid
11) Tetrad = 4 chromatid (Haploid #)
12) Crossing over – when chromosomes exchange segments to rearrange genetic information during
Prophase I of Meiosis
13) Homologous chromosomes – 2 chromosomes making up matched pair in a diploid cell
a. Same length, centromere position, and staining pattern
b. Possess genes for same traits at corresponding loci
c. 1 from father, 1 from mother
14) Autosomes – chromosome not involved in determining an organism’s sex
15) Sex chromosomes – determine organism’s sex
16) Gametes – reproductive cells (egg/sperm)
17) Chiasmata – microscopically visible site where crossing over has occurred between chromatids of
homologous structures during Prophase I of Meiosis
18) Somatic cell – typical body cell
19) Karyotype – micrographs of the metaphase chromosomes of a cell (nucleus)
20) Karyokinesis – division of nucleus
21) Gametogenesis – creation of gametes within gonads
22) OOgenesis – creation of mature egg cells
23) Spermatogenesis – creation of sperm cells
24) Polar bodies – byproducts of primary/secondary oocyte at each point of meiotic division in oogenesis
(not in spermatogenesis)
25) Girls are born with their eggs already made in Prophase I; puberty comes during Metaphase II
26) Prophase is longest phase of Meiosis
27) Klinefelters – XXY (when a male has an extra X chromosome)
28) Metafemale – XXX (when a female has an extra X chromosome)
29) Turners Syndrome – X0 (45 chromosomes in female, where they lack another X chromosome)
30) Not viable – Y0
31) Mitosis – growth/repair
a. One diploid parent cell divides to form 2 genetically identical daughter cells
b. Used for asexual reproduction in unicellular organisms
c. Cell cycle = 90% Interphase, 10% Mitotic phase
d. Interphase
i. G1 – cell grows + carries out normal metabolism; organelles duplicate
ii. S – DNA replication + chromosome duplication
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BIO 101 – Exam #2 Study Guide
iii. G2 – construction of spindle apparatus; chromosomes condense; cell continues growing
e. Prophase – nuclear envelope + nucleoli disappear
i. Spindle fibers begin to form
ii. Chromosomes begin to supercoil and are visible for 1st time
iii. Centrosome head to poles of cell
f. Metaphase
i. Spindle fibers fully formed
1. Attached to all of the kinetochores
ii. Centrosome are on polar sides of cell
g. Anaphase
i. Sister chromatids pulled apart at centromere by spindle fibers retracting, resulting in 1
member of each sister chromatid pair moving into a new cell
h. Telophase
i. 2 daughter cells have clear body
ii. Spindle fibers start disappearing
iii. Nucleoli reappears
iv. Chromosomes uncoil
i. Cytokinesis – division of the cell/cytoplasm to form 2 separate daughter cells
i. Cleavage furrow forms
32) Meiosis – egg/sperm (sexual cell division)
a. One parent cell (2n) divides to form 4 haploid daughter cells which are then processed into
gametes
b. Meiosis I – homologous chromosomes separate
i. Interphase I – chromosomes duplicates  each chromosome has 2 genetically identical
sister chromatids
ii. Prophase I – crossing over occurs  tetrad forms as a result of synapsis
iii. Metaphase I – spindle microtubules attached to a kinetochore
iv. Anaphase I – sister chromatids remain attached  homologous chromosomes separate
toward 2 poles of cell
v. Telophase I + Cytokenesis – cleavage furrow forms
c. Meiosis II – sister chromatids separate during Anaphase II
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