Chapter 2: Mitosis and Meiosis Flashcards
viruses DO NOT
contain DNA
an organisms DNA and genes are organized into
structures called chromosomes
in eukaryotes genetic continuity of genetic material involves
mitosis and meiosis
define chromatin
uncoiled chromosomes
prokaryotic cells include
bacteria and archaea
eukaryotic cells include
protists, plants, fungi, animals
what allowed scientists to see the cell in its highly organized structure?
electron microscopy
cell components which are directly or indirectly involved with genetic processes are
nucleolus
ribosome
centriole
the nucleolus contains
- rRNA synthesized and initially asembled
- nucleolus organizer region (NOR)
the NOR are portions of
DNA that encode for rRNA
the smooth ER is the
site of lipid synthesis
the rough ER is the site of
protein synthesis
centrioles are
cytoplasmic bodies found in centrosomes
centrioles organize
spindle fibers
spindle fibers are composed of
microtubules consisting of tubulin protein
chromosomes exists as _____ _____ in diploid organisms.
homologous pairs
a metacentric chromosome has the centromere located in the ______ of the chromosome.
middle
a submetacentric chromosome has the centromere located in the ______ of the chromosome.
between the middle and the end
a acrocentric chromosome has the centromere located in the ______ of the chromosome.
close to the end
a telacentric chromosome has the centromere located in the ______ of the chromosome.
at the end
the haploid number is
-half of diploid number
the haploid number constitutes
genome of species
what is a karyotype?
number and visualization of chromosomes in a cell
what is ploidy?
the number of sets of homologous chromosomes in the genome of a cell or an organism
homologous chromosomes have identical
locus
which type of chromosomes are not always homologous?
sex-determining chromosomes
what is karyokinesis?
genetic material evenly divided into two nuclei
what is cytokinesis?
cytoplasmic division
the cell cycle is composed of
interphase and mitosis
interphase is composed of
G1, S, G2
S phase occurs in
nucleus where DNA is duplicated
G1 and G2 occurs in
cytoplasm
G0 phase is a point where
cells withdraw from cell cycle and enter a non-dividing but metabolically active state
(happens in G1)
most of the cell cycle is in
interphase
the average human completes the cell cycle in
about 16 hours
what are the discrete stages of mitosis
prophase prometaphase metaphase anaphase telophase
describe what happens during prophase
chromosomes coil up and condense; centrioles divide and move apart
describe what happens during prometaphase
chromosomes move to metaphase plate of cell due to spindle fibers bonding to kinetochores and moving the chromosomes
what is cohesion?
a protein complex that holds sister chromatids together
what enzyme degrades cohesion?
separase
what is shugoshin?
“guardian spirit” that protects cohesion at the centromere while chromosomes are lining up on the metaphase plate
describe what happens during metaphase
centromeres of chromosomes are aligned at the metaphase plate
describe what happens during anaphase
disjunction occurs; chromosomes migrate to opposite poles
what are the 3 things that need to happen for disjunction to be successful?
- shugoshin is degraded
- cohesion is cleaved
- sister chromatids are pulled to opposite ends of the cells
describe what happens during telophase
- chromosomes uncoil
- nuclear envelope reforms
- spindle fibers disappear
- nucleolus reforms
division of the cytoplasm is known as
cytokinesis
what do kinases serve as?
“master control” molecules
what binds with kinases?
cyclins
what two proteins activate cellular activity
kinases and cyclin
the 3 major checkpoints are checked by? where do these checkpoints occur?
- master control molecules (kinases)
- G1, G2, M
meiosis maintains
genetic continuity from gen. to gen.
meiosis gives rise to genetic variation by
crossing over
independent assortment
meiosis I is known as the
reductional division
meiosis II is known as the
equational division
where does crossing over occur?
chiasma (prophase I)
what is terminalisation?
when centromeres attach to spindles and nuclear envelope breaks down
disjunction is when
half of each tetrad is randomly pulled to opposite poles
spermatogenesis begins with
spermatogonium germ cell
the spermatogonium becomes
primary spermatocyte
primary spermatocyte undergoes mitotic division and produces
haploid secondary spermatocytes
secondary spermatocytes undergo
meiosis II
oogenesis begins with
oogonium
the oogonium enlarges and becomes the
primary oocyte
what are the two characteristics to the meiotic division that produce daughter cells during oogenesis?
- receive equal amounts of genetic material
- do NOT receive equal amounts of cytoplasm
what receives the bulk of cytoplasm?
the secondary oocyte
what is a polar body?
cell with little to no cytoplasm
secondary oocyte undergoes secondary division and produces
an ootid and a 2nd polar body
secondary division is completed
after fertilization
human chromosome 1 is made up of how many nucleotides and genes?
-about 250 million nucleotides
2,000 genes
