Lecture 1: Chromosome Structure, Prokaryotic and Eukaryotic Cell Division, Mitosis, and Meiosis

t/f: all life has a genome

true

t/f: the Prokaryotic genome is comprised of DNA that is free flowing in the cytoplasm of the cells (not contained in a nucleus)

true

t/f: eukaryotic cells have a nucleus which is a

membrane bound compartment which holds most of

the organism’s DNA (the nuclear genome).

true

Prokaryotic Archaea

• cell size: 0.1 - 5 um

• no nucleus or membrane-bound organelles

• can be haploid or polyploid genome copies of circular DNA

• can have plasmids and chromatin

• reproduce asexually (binary fission)

Bacteria

• 0.1 to 5.0 um

• no nucleus or membrane-bound organelles

• haploid circular DNA

• can have plasmids

• reproduce asexually (binary fission)

Eukaryotic Archaea

• 10 to 100 um

• nucleus with internal membrane-bound organelles

• polypoid of linear chromosomes (DNA + Histones) in nucleus

• have organelles with own bacteria-like DNA (mitochondria)

• asexually via mitosis and sexually

  via meiosis

What is the life system of informational flow?

central dogma

replication then transcription then translation

replication

before cell division, during s phase DNA is replicated using DNA polymerase so each daughter cell has comeple genome copy

Transcription

• DNA is transcribed into RNA via RNA polymerase during

translation

RNA to protein

rna is translated via tRNA into amino acid chains which then become structure of proteins

ribosome play a key role

ploidy

the number of sets of unique chromosomes in a cell

• diploid = two sets of chromosomes

• haploid = one set of chromosomes

homologous chromosomes

the same type of chromosome that is inhertied from differnt parents

• homologs have the same gene regions but can differ in DNA sequence

ex: one homolog has A and the other has G

t/f 3n means that the organism is triploid

true: it has 3 sets of unique chromosomes

t/f: Humans (diploid) each get a homolog from each of the two haploid cells (gametes) that fuse together to make a zygote

true

t/f: in bacteria DNA replication and cell division occur at the same time

true: it is called binary fission

t/f: cell division and DNA replication happen at the same time for eukaryotic and prokaryotic Archaea cells

false: they happen in two seperate processes

life cycle of a cell

G1, then G0, then G1 then Interphase (S-phase) then G2 then Mitosis then repeats

t/f: s-phase is where DNA replication occurs and results in sister chromatids

true

Mitosis (cell division) order

prophase, metaphase, anaphase then telophase

sister chromatids

duplicated of chromosome made up of two chromatids (DNA molecules) and are held together by cohesion

t/f: sister chromatids are identical chromosome of each homologous chromosome

true

Mitosis prophase

• nuclear envelope disappear

• chromosome condense

• spindle forms

• sister chromatids attach to microtubules from from opposite centrosomes

centromeres

non coding regions that have proteins where mitotic and meitoic spindles attach to each chromosome to allow equal division of DNA into daughter cells in mitosis and meiosis

mitosis metaphase

equal tensions allows for chromosomes align at middle of cell and cohesions keep sister chromate togther

mitosis anaphase

sister chromatids separate and move to opposite poles

mitosis telophase/cytokinesis

chromos decondense and nuclear envelope reforms, cell membrane forms to separate daughter cells

cytokinesis in plants

spindle MT;s HELP BUILD NEW CELL WALL

cytokinesis in animals

contractile ring pinches cytoplasm in two daughter cells

t/f: Mitosis is asexual cell division because it

leads to identical daughter cells while Meiosis is sexual cell division that leads to diverse meiotic

products

true

t/f: meiosis can happen at any ploidy level and mitosis can only happen at diploid or higher

false: mitosis can happen at any ploidy level and meiosis can only have a diploid or higher bc it reduces ploidy

chisma

the physical points of crossover along

homologous chromosomes.

meiosis prophase I

• homologs paris to make tetrads

• crossing over occurs

• meiotic spindles attache to each homolog

crossing over

happen between homologs and are the physical changes of DNA

t/f: Meiosis I is where plodiy is reduced

true: you start with 2n= 8 and end with each daugher cell has n=4

meiosis metaphase I

Meiotic spindle attaches to each homolog and they line up on the midline of the cell.

meiosis anaphase I

the pairs of homologs (tetrads) are separated to opposite poles of the cell but sister chromatids remain attached.

Meiosis prophase II

• chromosomes condense

• spindle forms

• sister chromatids are together

t/f: only germ cells undergo meiosis

true

Meiosis metaphase II

paris of sister chromatids line up in the middle of cell

Meiosis anaphase II

sister chromatids are pulled apart by mitotic spindles

Meiosis telophase/Cytokinesis II

• nuclear envelope forms

• chromosome deconde

• cytoplasm pinches and makes 4 haploid daughters

how many chromosomes mitosis of human cell before s-phase

chromosomes: 46

Chromatids: 46

diploid

how many chromosomes mitosis of human cell after s-phase

chromosomes: 46

chromatids: 92

diploid

how many chromosomes at the start of mitosis does human cell have

chromosomes: 46

chromatids: 92

diploid

how many chromosomes at the end of mitosis does human cell have

chromosomes: 46

chromatids: 46

diploid

how many chromosomes meiosis of human cell before s-phase

chromosomes: 46

chromatids: 46

diploid

how many chromosomes meiosis of human cell after s-phase

chromosomes: 46

chromatids: 92

diploid

how many chromosomes at the end of meiosis I does human cell have

chromosomes: 23

chromatids: 46

haploid

how many chromosomes at the end of meiosis I does human cell have

chromosomes: 23

chromatids: 23

haploid