Ch2 Mitosis & Meiosis

1 strand of double sided DNA =

1 chromosome

how many cells are there in the human body

30 trillion (3 × 10¹³)

somatic cells

cells that stay with you till you die (daughter cells)

46 chromosomes

mitosis

germline cells

contribute to the genetic info of the next generation (sex cells)

23 chromosomes

meiosis

what is 2n , and what does n represent

2n = diploid

n = haploid number (23 for humans)

• has all the unique genetic info for that species

transmission electron microscopy

see cells’ organized structure in high resolution

the cell components involved with genetic processes are:

nucleolus, ribosome, and centriole

________ and ________ have their own genetic info

mitochondria & chloroplasts

how many base pairs does mitochondria have ?

16,000 base pairs

what is the size of a genome

3 billion (3 × 10⁹)

all cells are surrounded by a ________ (made of _______)

what does it do ?

plasma membrane , made of lipid bilayer

it defines cell boundary, control movement of material in & out of cell

plant cells have an outer covering in addition to plasma membrane, what is it made of?

cell wall; made of cellulose polysaccharide

animal cells are surrounded by a cell coat called _______, what is its purpose ?

Glycocalyx .

serves as recognition sites at cell surface

where is rRNA synthesized and assembled ? where are portions of DNA that encode for rRNA located?

rRNA is synthesized in the nucleolus, and in the NOR (nucleolus organizer region) is where DNA encodes rRNA

what is a cytoplasm and what are the contents inside of it and their purposes ?

cytoplasm is the remainder of the cell excluding nucleus (earth)

cytosol : liquid portion in the cytoplasm (oceans)

cytoskeleton : made of microtubules (tubulin) & microfilaments (actin) to provide support and cell movement

Italicize the name of the ______ not the ______

Italicize the name of the gene not the protein.

ER

smooth ER: lipid synthesis & detoxify
rough ER: ribosomes on the outside; protein synthesis

what do ribosomes do ?

genetic info in mRNA is translated to protein

mitochondria

site of ATP synthesis & oxidative phases in cell respiration

mtDNA

chloroplasts

site of photosynthesis

cpDNA

centrioles

organize spindle fibers for meiosis & mitosis

what are spindle fibers made of ?

microtubules

where do the sister chromatids divide ?

centromere

Locations of centromere

Metacentric: middle

Submetacentric: between middle & end

Acrocentric: close to end

Telocentric: at the end

what are homologous chromosomes?

a pair of chromosomes with the same genes, dif alleles

• identical gene sites (loci)

karyotype

number of chromosomes

How many genes do fruit flies have ?

14,000 genes

how many genes do humans have ? and how many genes are there for 1 chromosome for humans?

20,000 genes ; 1 chromosome = 500-2000 genes

a gene is :

all the DNA sequences needed to create that gene product

Ken & Barbie fruity fly gene mutation is for what ?

mutation that causes lack of genitalia

“white” fruit fly gene mutation name is for ?

mutation that causes white eyes

zygote

first diploid cell

karyokinesis

genetic material divided into 2 daughter cells (2 nuclei) during nuclear division

cytokinesis

after karyokinesis; when the 2 daughter cells split each is enclosed by plasma membrane

Cell Cycle

Interphase:

G0: non dividing cells go here & stay (quiescent)
G1: cell grows

S phase: gene duplication creates sister chromatids with cohesin to hold them tg

G2: cell grows & checks for DNA errors

Mitosis

around 16 hours total

Mitosis stages

1. Prophase: chromosomes condense & centrioles divide and move apart

2. Prometaphase: chromosomes are visible double structures; centrioles reach opposite sides and spindle fibers form.

3. Metaphase: centromeres align on the metaphase plate & spindle fibers bind to kinetochore to pull the chromosomes

4. Anaphase: centromeres split & daughter chromosomes move to opposite sides (disjunction)

5. Telophase: daughter chromosomes are at opposite poles; cytokinesis divides cytoplasm, nuclear envelope reforms and interphase begins again.

what degrades Cohesin during prometaphase/metaphase? What are where is degradation prevented?

Cohesin is degraded by enzyme separase.

Enzyme shugoshin prevents degradation of cohesin at centromere

what do kinases do , and which protein is it activated by ?

tells cells when to proceed to the next phase; activated by cyclins

Where are the 3 major cell cycle checkpoints & what do they do? What happens if they fail?

G1,G2, and Metaphase

It checks for DNA errors, and if so the cell will try to repair, if it cant its removed and self destructs (apoptosis) . If failed, tumors & mutations can result.

Events of Meiotic Prophase 1

1. Synapsis: 1 chromosome from each parent combines to create a bivalent

2. Chromosomes condense and create 4 chromatids total = tetrad

3. Chromosome arms cross e/o = chiasma

4. Terminalization: Chiasmata move towards the ends

what is half of a tetrad ?

Diad

Spermatogenesis

production of male gamete in testes

1. Spermatogonium replicates itself and creates Primary Spermatocyte

2. Meiosis 1: Primary Spermatocyte divides into 2 = Secondary Spermatocytes

3. Meiosis 2 : Secondary Spermatocytes divide into 2 = 4 Spermatids

4. Spermatids develop into Spermatozoa (differentiation)

Oogenesis

production of female gamete in ovaries

1. Oogonium replicates itself into Primary Oocyte

2. Meiosis 1: Primary Oocyte divides into a smaller First Polar Body (which dies) and into a larger Secondary Oocyte.

3. Meiosis 2: Secondary Oocyte divides into a smaller Secondary Polar Body (which dies) and a larger Ootid.

4. Ootid becomes Ovum (differentiation)