Mitosis Flashcards
Why does a prokaryotic cell divide?
It is reproducing, gives rise to a new organism (cell). This is the same for unicellular eukaryotes (like amoeba)
Why does a multicellular eukaryotic cell divide?
It enables each organism to develop from a single cell (fertilized egg) / growth and development; asexual reproduction; tissue renewal
What eukaryotic cells never divide?
Mature nerve and muscle cells
What is the crucial function of most cel divisions (besides meiosis)?
The distribution of identical DNA to 2 daughter cells
What is the genome?
A cell’s DNA/genetic info
What is the prokaryotic genome?
often a single DNA molecule
What is the eukaryotic genome?
multiple DNA molecules because they are packaged into chromosomes
What is chromatin?
the entire complex of DNA and proteins that together build chromosomes
What are somatic cells?
All body cells except reproductive cells
How many chromosomes are in each nuclei of a human somatic cell?
46 chromosomes in 2 sets of 23, 1 set inherited from each parent
What are gametes? How many do humans have?
reproductive cells (egg or sperm); 1 set of 23 chromosomes
what is a sister chromatid?
identical copies of a replicated chromosome, joined at the centromere, that are separated during cell division (mitosis or meiosis) to ensure each new cell receives a complete set of chromosomes
what are some features of sister chromatids?
- each contain an identical DNA molecule
- attached all along lengths by protein complexes called cohesins
- each has a centromere (a region made of repetitive sequences in chromosomal DNA where sister chromatids are most closesly attached)
what happens when sister chromatids separate from each other?
- they move into 2 new, separate nuclei
- after separation they are individual chromosomes
- this step double # of chromosomes during cell division
what is mitosis?
the division of genetic material in the nucleus
what happens after mitosis?
cytokinesis (division of the cytoplasm)
what is meiosis?
a type of cell division which yields daughter cells with only one set of chromosomes, producing gametes (in humans, only occurs in ovaries or testes/gonads for gametes)
how is a chromosome duplicated and distributed during cell division?
1) chromosome is a long, thin chromatin fiber containing one DNA molecule and associated proteins
2) once duplicated, the chromosome consists of 2 sister chromatids connected by sister chromatid cohesion
3) molecular and mechanical processes separate the sister chromatids into 2 chromosomes and distribute them to 2 daughter cells
What does the cell cycle cover?
The life of a cell from when it’s first formed during division of parent cell
-> its own division into 2 daughter cells
What happens in the mitotic phase (M)?
Both mitosis and cytokinesis, the cell physically divides into 2
what is usually the shortest part of the cell cycle?
the mitotic phase (M)
what is alternated with the mitotic phase?
interphase
what is interphase? what stages does it include?
~90% of the cell cycle, a growth period where a cell grows by producing proteins and cytoplasmic organelles (like mitochondria and endoplasmic reticulum)
1) G1 phase (first gap)
2) S phase (synthesis)
3) G2 phase (second gap)
what happens during G1 phase (first gap)?
cell grows by producing proteins and organells