BIO 1510 Chapter 10 and 11

Mitosis

When parent cell divides ONCE to produce 2 genetically offspring

Chromosomes are made of

chromatin

A somatic cell has

46 chromosomes

kinetochore

Protein complex to which microtubules that separate chromosomes during celkl division

Telomeres

Repetitive non-coding DNA sequences which protect chromosomes from degration by nucleus

Telomeres are found at the end of

chromosomes

Karyotype

Picture of all chromosomes in a single cell

When chromosomes are loose, you cannot

distinguish them

Chromosomes 1-44 are

autosomes, nonsexual

23rd pair

sexual

Heterochromatin

Tightly packed chromatin whos DNA is tightly packed and cannot be used to make proteins

Heterochromatin location

At the centromere and telomere

Euchromatin

loosely packed chromatin who makes protein

Histones

in eukaryotes but not bacteria

histones include

H1,H2A, H2B, H3, H4

Histone core consists of 8 core histones:

2h2a,2h2b,2h3,2h4

H1 is the

linker histone

G0

Non-dividing phase where two mature skeleton muscle and nerve cells stop permanently

G1

Cell grows but doesnt divide

S

Cell duplicates is DNA and chromosomes, and centrosome duplication begins

G2

Cell still grows and centrosome duplication ends

Centrosome/MTOC

Region of cytoplasm from which microtubules grow out, forming mitotic spindle that guides the separation of chromosomes during cell division

Centrioles only replicate

Animal cells

Cell has

2 centrosomes
2 centrioles
2 Sister chromatids
Held together cohesion protiens

Solenoid

When H1 pulls nucleosomes together

Chromatin loops forms when

solenoids coil around eachother

DNA packaging

5 steps

Rosettes condense to form a tightly packed chromosomes as seen in

mitosis

Prophase

Chromosomes become visable, nuclear envelop dissolves, spindle forms

Prometaphase

The second stage of mitosis, in which the nuclear envelope fragments and the spindle microtubules attach to the kinetochores of the chromosomes.

Metaphase

Chromosomes line up in the middle of the cell

Metaphase chromosome is condensed because of

condensin protiens

The mitotic spindle at metaphase

1) kinetochore microtubule
2) Aster microtubule
3) Polar Microtubules

Anaphase

Phase of mitosis in which the chromosomes separate and move to opposite ends of the cell

Telophase

After the chromosome seperates, the cell seals off, Final Phase of Mitosis.

Before telophase ends

cytokinesis begins

cytokenisis in animal cells

At the end of the M phase, two daughter cells are produced, which are genetically identical to each other and to the parent cell

Contractile

Ring of actin filaments in cyto

contracile ring and cleavage furrow is only in

animal cells

Cell material together with phragoplast form a

cell plate

phragmoplast

An alignment of cytoskeletal elements and Golgi-derived vesicles across the midline of a dividing plant cell.

G1/S checkpoint

Cell "decides" to divide
Primary point for external signal influence

G2/M

cell monitors DNA synthesis and damage

spindle checkpoint

ensures that all of the chromosomes are attached to the spindle in preparation for anaphase

Cyclin-dependant kinases (Cdks)

A protein kinase that is active only when attached to a particular cyclin.

inhibitory phosphate inhibits

CDKs

Cyclin proteins that helps activate

CDK

CDK activates when cyclin and

activating p are attached to it

CDK is inactive when

cyclin and both activating and inhibitory phosphate are attached to it

Anaphase promoting complex

A protein complex that triggers the separation of sister chromatids and orchestrates the carefully timed destruction of proteins that control progress through the cell cycle; the complex catalyzes the ubiquitylation of its targets.

APC is at the end of

M

Proto-oncogenes

Code for proto-oncogene proteins that stimulate cell division (Ras and Src)

Oncogenes can cause

Cancer

tumor suppressor genes

Encode tumor suppressor proteins that inhibit cell division (p53 and Rb)

Retinoblastoma

Cancer that affects the retina

Sre kinase

Sacroma, cancer that affects muscles, bones, and other connective tissues

p53

This tumor suppressor gene causes cell cycle arrest in G1, providing time for DNA repair. If repair is successful, cells re-enter the cycle. If unsuccessful, apoptosis

Abnormal p53

p53 protein is non functional

Ras protien activated by mutations in

20-30 percent of all cancers

Src kinase

acivated by mutations in 2-5 percent of cancers

Rb protein mutated in

40 of all cancer

p53 mutated in

50 of all cancer

Cohesion is not in

telophase

the second checkpoint is at the end of

G2

p53 codes for

for a protein that regulates the cell cycle and hence functions as a tumor suppression.

somatic cells

any cell of a living organism other than the reproductive cells.

meiosis produces

4 gametes

Gametes

sex cells

mitosis creates

2 somatic cells

Both meiosis 1 and 2 have

PMAT

Human germ line cells

interphase-meiosis 1-interphase-meiosis 1-Interphase-meiosis 2

Meiosois: 2n =

n n n n

Mitosis: 2n

2n 2n

Mitosis= n

n n

prophase 1

Chromosomes become visible; nuclear envelope breaks down; crossing-over occurs.

Tetrad

structure containing 4 chromatids that forms during meiosis

tetrads consist of

4 chromatids

synaptonemal complex

Layer of proteins thats holds 2 homologous chromosomes together

Crossing over

the exchange of genes between homologous chromosomes, resulting in a mixture of parental characteristics in offspring.

Prophase 1 is unique to

synapsis, formation of tetrads and crossing over

metaphase 1

tetrads line up at the metaphase plate, with one chromosome facing each pole

kinetochore are attached to the

kinetochores of 1/2 of chromatids

what leads to genetic variation

crossing over
independent assortment

Pairs of homologous chromosomes seperate because

synaptonemal complex is destroyed

anaphase 1

homologous chromosomes separate and are pulled to opposite ends of the cell

at metaphase 1

tetrad of 2 homologous chromosomes held together by synaptonemal complex is found on the metaphase plate

at anaphase

cohesion proteins are destroyed, allowing sister chromatids to come apart

telophase 1

Cytoplasm divides, 2 daughter cells are formed

prophase 2

the nuclear envelope breaks down and the spindle apparatus forms

metaphase 2

Centromeres of chromosomes line up randomly at the equator of each cell.

the number of potential gametes can be predicted using

2nm where n is the haploid number of chromosomes

in meiosis 1, two daughter cells are

not identical

in mitosis, two daughter cells are

identical

know all of the

pictures of the phases

in meiosis, the chromosomes replicate at

meiosis 1 and 2

homologous chromosomes are found in gametes

false

Meiosis determines how we

look

1st law of heredity

law of segregation

Law of Segregation

Mendelian law stating that two alleles for each trait separate during meiosis

alleles for eye color segregate during

anaphase 1