12.6 Cell Cycle & Cell Division Flashcards
what is the first stage of the cell cycle called
interphase
what 3 stages is interphase divided into
G1 phase (gap 1)
S phase (synthesis)
G2 phase (gap 2)
what happens in G1 phase
cell increases in size / volume and new biomass is made (proteins)
what happens in S phase
DNA replicates by semi-conservative DNA replication
what happens in G2 phase
cell prepares for division, synthesis and stores of ATP and new organelles synthesised
nuclear division (mitosis or meiosis) definition
period when the nucleus divides into 2 (mitosis) or 4 (meiosis)
cell division (cytokinesis) definition
division of the cytoplasm which follows nuclear division and is the process by which the cytoplasm divides to produce 2 new cells (mitosis) and 4 new cells (meiosis)
why does the mass of a cell in the cell cycle overall increase
- G1 -> cell gets bigger -> more mass
- S -> DNA replication
- Mitosis -> organelle replicate
why does the mass of DNA in the cell cycle increase and then decrease
increases in S phase -> DNA replication
decreases in mitosis -> DNA contents halves as cell divides into 2 during cytokinesis
gene definition
a section of DNA that codes for 1 specific polypeptide (protein)
the base sequence of DNA on the DNA codes for…
the sequence of amino acids in a protein
chromosome definition
an independent DNA molecule which has been supercoiled into a condensed form
unduplicated chromosome is called
chromatid
duplicated chromosome is called
identical sister chromatids
central point in chromosome is called
centromere
how are identical sister chromatids formed
DNA starts to coil around histones -> DNA supercoils and condenses -> Forms identical sister chromatids
why do complex organisms have a number of chromosomes
they have a large number / many different genes
what is a chromosome number
the number of different chromosomes possessed by an organism
the chromosome number is represented by the letter…
n
diploid (chromosome number)
2n
haploid (chromosome number)
n
draw a single unduplicated chromosome
draw a single duplicated chromosome
a single unduplicated chromosome. before or after S phase
before S phase