Chapter 2: chromosome and cellular reproduction Flashcards
what happens before cell division
-dna chromosome replicates, after replication there are two copies of sister chromatids
what are some characteristics of a prokaryotic cell
- pro does not have a nuclear membrane or nuclues
- cell is small
- one circular dna
- no membrane bound organelles
what are some characteristics of a eukaryotic cell
- nucleus is present
- cell is big and complex
- large dna
- membrane bound organelles
what is binary fission
asexual reproduction where a parent cell divides into 2 identical cells used by bacteria and archea
what is the process for cell reproduction in bacteria
- pro cell contains one single circular chromosome that is made of double stranded dna
- as the chomosomes replicate the origins segreagate to opposite sides
- the cell divides into identical copies
what is the origin of replicaiton
it is where the dna sequence begins replication
LO 2.6: describe what a diploid organism is and what homologous chromosomes are
- diploid organism has 2 sets of chromosomes
- homologous chromosomes have the same genes and one comes from mom and one set comes from dad
what are sister chromatids
two identical copies of a chromosome that are formed by dna replication
how many pairs of chromosomes does a human have
23
how many total chromsomes does a human have
46 chromosomes
what are the stages of the cell cycle before mitosis
interphase which is g1, s phasee, g2 phase
where does the cell spend most of its time in the cell cycle and what happens during that stage
in interphase and it is where cell growth happens
what happens in the mitosis phase
nuclear and cell divison
what is the purpose of mitosis
to produce 2 genetically identical cells
what is the purpose of meiosis( gametogeneis)
to create gametes for sexual reproduciton
what are the results of meiosis
4 genetically variable cells who have 1/2 chromosome numbers
what is one difference between meiosis 1 and meiosis 2
reduction divison: chromosome number is 1/32 and then equational division” similar to mitosis
what is interkinesis
the stage that is in between meiosis 1 and meiosis 2 and it is when the chromosomes become relaxed and the nuclear membrane begins to form again
what happens in prophase 1 of meiosis
- chromosomes condense.
-crossing over takes place - nuclear membrane breaks down
- miotic spindle forms
metaphase 1
- homolog chromosomes line up on the metaphase plate
anaphase 1
homolog chromsomes separate and go toward opposite poles
telophase 1
chromosomes arrive at the spindle poles
cytokinesis 1
cytoplasm divides to produce two cells each having halve the og number
prophase 2
- chromosome condense
- spindle forms
- nuclear memebrane disentegrates
metaphase 2
sister chromatids line up on the metaphase plate
anaphsae 2
sister chromatids separate and the individual chromosomes move toward opposite poles
telophase 2
chromosomes arrive at the spindle poles
- spindle breaks down and a nuclear envelope forms
how is genetic variation created in meiosis
through crossing over and random distribution of chromiosomes during metaphase 1
how does cohesin control the separation of chromatids and chromosomes in mitosis and meiosis
cohesin holds the homologous chromosomes together st th chiasmata and it can also break down so that the homologs to separate
when does male spermatogenesis occur
from puberty through adulthood
- produces 4 sperm cells for each round of meiosis
when does female oogenesis begin
prior to birth and is not complete until after fertilization
- 1 egg is produced for each round of meiosis