Mitosis-Meiosis

Front 1

Chromatin

Back 1

Chromosome when cell is not dividing -A tangle of fibers composed of protein and DNA, located in the nucleus of a cell

Front 2

Chromosome

# in somatic cell

# in gamete

Back 2

Composed of 1 DNA molecule and associated proteins
46 /23 pairs
23

Front 3

Cell cycle

Back 3

Life history of actively dividing cells

Front 4

3 Stages of Interphase

Back 4

G1, S, G2

Front 5

During G1

Back 5

Cell doubles in size
Organelles and enzymes double in number

Front 6

Restriction Point

Back 6

Point at which it is determined whether or not cell will go on to S phase and continue to divide or become non dividing - G0 phase

Front 7

Describe S phase

Back 7

The two strands of DNA:
unwind, separate, replicate
into two helices of DNA
= Chromatids attached
@ centrinomes

Front 8

During G2 phase

Back 8

Spindle fibers assemble

pair of centrioles (in animals) divide

both involved in movement of chromosomes during mitosis

Front 9

.Prophase Events

Mitosis

Back 9

Chromatin fibers coil and condense

centrioles migrate to opposite poles

Mitotic spindle begins to form

Front 10

Prometaphase

Mitosis

Back 10

Chromosomes more condensed

Nuclear envelope fragment

each chromatid has kinetochore at centrinome

some microtubules attach to kinetochores

others interact with those from opposite poles

Front 11

Metaphase

Mitosis

Back 11

longest phase

chromosomes line up on metaphase plate

kinetochore of sister chromatids are attached to microtubules from opposite poles

Front 12

Annaphase

Mitosis

Back 12

shortest phase

cohesion proteins are cleaved

chromatids part becoming chromosomes

cell elongates as nonkinetichore microtubules lengthen

ends with two sets of chromosomes at opposite ends of cell

Front 13

Telophase

Mitosis

Back 13

Two daughter nuclei form

Nuclear envelopes reform

Nucleoli reappear

Chromosomes become less condensed

Mitosis complete

Division of cytoplasm begins

Front 14

Cytokinesis

Mitosis

Back 14

formation of a cleavage furrow
(in animals) which pinches cell in two

in plants a cell plate forms -grows into cell wall

Front 15

Prophase I

Meiosis

Back 15

Chromosomes begin to condense

Homologs loosely pair along lengths

Crossing over is completed while homologs are in synapsis

Synapsis ends -chromosomes in each pair move slightly apart

each pair has one or more chiasmata

homologs still associated due to sister chromatid cohesion

Front 16

Synapsis

Back 16

homologs are held tightly together by proteins along their lengths

in prophase meiosis

Front 17

chiasmatsa

Back 17

points where crossing over has occurred

prophase I meiosis

Front 18

Late prophase 1

Back 18

microtubules from one pole or other attach to kinetochores at the centromeres of the two homologs

homologs move towards metaphase plate

Front 19

Kinetochores

Back 19

specialized protein structure located at the centromere

location microtubules connect during prometaphase - mitosis
prophase 1 meiosis

Front 20

Common in prophase for both mitosis and meiosis

Back 20

Centrosome movement

spindle formation

nuclear envelope breakdown

Front 21

Metaphase I

Back 21

Pairs of homologous chromosomes line up on metaphase plate

BOTH chromatids of ONE homolog are attached to kinetochore microtubule from one pole /same for other homolog from opposite pole

Front 22

Anaphase I

Back 22

Sister chromatid cohesion proteins break down enough to let homologs separate

cohesion persists at sister chromatid centromere

chromatids move as unit as homologs separate and move to opposite poles

Front 23

Telophase 1
and
Cytokinesis

Back 23

Cytokinesis occurs simultaneously

Two haploid cells form

Each chromosome = two sister chromotids

Front 24

Cytokenisis

Back 24

Division of cytoplasm

Front 25

Prophase II

Back 25

A Spindle apparatus forms

sister chromatids move towards metaphase plate

Front 26

Metaphase II

Back 26

Chromosomes positioned on metaphase plate

due to crossing over - sister chromatids are not genetically identical

kinetochores of sister chromatids are attached to microtubules from opposite sides

Front 27

Anaphase II

Back 27

Proteins holding sister chromatids together at centromere break down

Chromatids separate and move to opposite poles as individual chromosomes

Front 28

Telophase II
and
Cytokinesis

Back 28

Nuclei form

Chromosomes begin decondensing

Cytokinesis occurs

there are now 4 haploid daughter cells each genetically different from the other and from the parent cell

Front 29

Haploid Cell

Back 29

Cell containing only one set of chromosomes

23 chromosomes

Front 30

Diploid Cell

Back 30

Cell containing two sets of chromosomes (2n), one from each set of parents

23 pairs
46 chromosomes

Front 31

Nuleoli

Back 31

Non-membrane bound structures composed of proteins and nucleic acids found within the nucleus where ribosomal RNA (rRNA) is transcribed and assembled.

Front 32

Mitotic Spindle
consists of

Back 32

Astral fibers (short that surround the centrioles),

spindle fibers that attach to the chromosomes,

spindle fibers that extend between centrioles

Front 33

How do protein kinases and cyclins regulate the cell cycle?

Back 33

Protein kinase enzymes control cell cycle activity by phosphorylating regulatory proteins called cyclins which in turn can regulate protein kinase. Specific Cdk (cyclin depentent kinase) enzyme complex is required for cells to pass the restriction point

Front 34

Centrosome

Back 34

Microtubule organizing center, has a pair of centrioles

Front 35

Centriole

Back 35

A structure in the centrosome composed of microtubule triplets arranged in a 9+0 pattern

Front 36

Tetrad

Back 36

For Chromatids or two dyads

(a homologous pair of two chromatids)

Front 37

Spindle fibers

function

lengthen and shorten by

Back 37

Move chromosomes

the addition and loss of tubulin subunits