Biology Lecture 12

Cell Cycle and Cell Division

Interphase

DNA replication occurs, cells make extra proteins and organelles in preperation, not part of mitosis

interphase

majority of a cells life

all cells

which cells go through interphase

G1 stage

majority of interphase, cells grow and work, “listen” for cues to divide

S stage

synthesis making- DNA replication, make a complete second copy of the nuclear DNA

G2 stage

make extra organelles and proteins

G0 stage

where the cells stop listening cues to divide and focus 100% on working, ex: neurons

checkpoints

proteins and enzymes that regulate the cell cycle, controls when cells divide and helps remove damaged cells

M checkpoint

is everyone attached to the spindle?

yes- anaphase

no- fix it or apoptis

G1 checkpoint

did the receive enough cues to divide?

yes- move onto S phase

no- keep working

G2 checkpoint

do we have a second copy of DNA? Extra proteins and organelles?

yes- on to prophase

no- correct the issue or apoptis

cyclins

messenger molecule/activator

apoptis

programmed cell death, removes damaged, aged, or unecessary cells without causing inflammation

G1, S, G2, G0

stages of interphase

binary fission

performed by prokaryotic cells, asexual reproduction, includes mitochondria and chloroplast, DNA is attached directly to the plasma membrane

prokaryotic cells

where does binary fission take place

eukaryotic cells

where does mitosis take place

mitosis

division of the nucleus, growth, repair/replacement, asexual reproduction

chromosome

a pair of identical DNA, helices held together by proteins

kinetochore

protein “handle” used during mitosis and meiosis

centrome

“waist” of the chromosome, location can vary across chromosomes

P arm

short arm of a chromosome

Q arm

long arm of a chromosome

chromatid

1 DNA helix

mitotic spindle

equally divide DNA helices to form 2 complete sets

microtubules

make up mitotic spindle, largest element of the cytoskeleton

astral microtubules

position the spindles

kinetochore microtubules

shrinks and pulls apart the chromosome

polar microtubules

grow and push the poles the apart

centrioles

found in pairs, only in animal cells, made of microtubules, help arrange the spindle fibers

prophase, metaphase, anaphase, telophase

mitosis stages

prophase

DNA condenses, nuclear envelope and nucleolus disappear, spindle forms and attaches to the chromosome

anaphase

chromosomes split, chromatids migrate to opposite sides

telophase

spindle disappears, DNA relaxes, nuclear envelope and nucleolus reappear

cytokinesis

division of the cytoplasm

telophase, not during mitosis

when does cytokinesis occur

meiosis

sexual reproduction

meiosis is sexual reproduction, mitosis is asexual reproduction

what is the difference between meiosis and mitosis

homologous chromosomes

homologs

chromatids

prophase 1, metaphase 1, anaphase 1, telophase 1, prophase 2, metaphase 2, anaphase 2, telophase 2

stages of meiosis

prophase 1

DNA condenses, homologous chromosomes are formed, crossing over occurs, nuclear envelope and nucleolus disappear, spindle forms and attaches

metaphase 1

homologous chromosomes line up, M checkpoint

anaphase 1

homologous chromosomes split, homologs migrate to opposite poles

telophase 1

cells may do some or all of the following:

DNA relaxes, nuclear envelope and nucleolus reappear, spindle disappears

interkinesis

optional phase, cells make extra proteins and organelles in preperation for meiosis

prophase 2

DNA condenses, homologs form, nuclear envelope and nucleolus disappear

metaphase 2

homologs line up, M checkpoint

anaphase 2

homologs split, chromatids migrate to opposite poles

telophase 2

DNA relaxes, nuclear envelope and nucleolus reappear, spindle disappears, incomplete split of cytoplasm

get rid of damaged cells, help shape our body during development, get rid of old cells

reasons to undergo apoptis

mitosis and cytokinesis

the process of cell division involves the two stages...

A

which is the astral microtubule

E

which is the kinetochore microtubule

D

which is the polar microtubules

no

does DNA replication occur during Mitosis

metaphase

what stage of mitosis is this

metaphase

The chromosomes line up randomly at the equator of the cell during

bacteria cells

this process if performed by

kinetochore

acts as a handle where a microtubule attaches to the chromosome

meiosis

chromosome number is cut in half (2n → 1n)

used to produce gametes

involved crossing over which increases diversity of offspring

involved in sexual reproduction

prophase

The chromosomes shorten and thicken, becoming visible, during

prophase

what is this stage of mitosis

telophase 2

Nuclear membrane reforms, cytoplasm divides, 4 daughter cells formed

interphase

The portion of the cell cycle when a cell is not dividing and instead performs normal cellular processes is called

mitosis

somatic cells undergo

meiosis

germ cells undergo

binary fission

bacterial cells undergo

2

diploid cells have how many copies of each chromosome

diploid

containing two complete sets of chromosomes, one from each parent

haploid

having a single set of unpaired chromosomes