Cell Division And Cell Cycle Flashcards
(25 cards)
What is mitosis used for?
Increasing cell growth and cell number of an organisms
Repair of damaged tissue
Replacement of dead cells
Produces 2 genetically identical diploid daughter cells but asexual reproduction
Describe interphase
The majority of the cell life is spent here
Consists of 3 stages which are:
1. G1= cell increases in size and volume amd new biomass is made
2.s = semi Conservative replication
3. G2= cell prepares for division by store of ATP and doubling the organelles
Describe prophase (4)
The nuclear membrane breaks down
The centrioles move to opposite end of cell and start to make spindle fibres
The chromatids supercoil and condense to form chromosomes and become visible
Each chromosome appears as 2 identical sister chromatids joined at its contromere
Describe metaphase (3)
The centrioles complete the production of spindle fibres
Spindle fibres attach to centromere of chromosome
The chromosomes align down the equator of the cell
Describe anaphase (4)
Spindle fibres shorten and contract
The contromere splits
Each identical sister chromatid are pulled to opposite ends of cells
Forming a v shape
Describe telephase (2)
The nuclear membrane reforms around each set of chromosomes
The chromosomes uncoil and become thinner and invisible
Allele definition
Different versions of the same gene
Gene definition
Section of DNA nucleotides that code for a polypeptide chain ( sequence of amino acids)
Chromosome definition
DNA associated with histone and appears in prophase as 2 identical sister chromatids joined by its centromere and contains many genes
Haploid definition
Cell that contain one copy of each chromosome
Diploid definition
Cells that contain 2 sets of homologous chromosomes
Somatic cell
A normal body cell
Homologous chromosomes
One maternal and one paternal chromosome and have same genes in same loci but different allels
Cancer definition
Uncontrolled cell division
What does the tumor suppressor gene code for
A protein that stops the cell cycle
What does the proto onco gene code for
A protein that starts the cell cycle
Mutation definition
A random spontaneous change in the DNA base sequence leading to change in the number and sequence of amino acids in a polypeptide chain
Binary fission in bacteria
Replication of circular DNA
Replication of plasmids
Division cytoplasm forming 2 daughter cells
Mitotic index equation
Number of cells in mitosis / total number of cells in field of view
How to make sure mitotic index is accurate
Examine large field of view or more cells
Repeat count so figures are correct
Only count whole cells
Repeat to find a mean
What does meiosis produce
4 genetically different haploid daughter cells sexually.
Describe what happens in meiosis 1 ?
P1 and m1 = chromosomes supercoil and condense and come visible. Homologous chromosomes pair up and align down the equator of the cell. Independent segregation and crossing over occurs here
A1 = spindle fibres contract and pull Homologous chromosomes to each end to cell
T1= nuclear membrane reforms and forms 2 haploid daughter cells
Describe what happens in meiosis 2?
P2 = each daughter cell ahead one chromosomes from each homologous pair
M2 = they align down the equator of the cell
A2 = non identical chromatids split but thier centromere to opposite ends of cell
T2 = nuclear membrane reforms
Crossing over
Homologous chromosomes associate and form a bivalent
Chiasmata forms where they entangle
Equal lengths of non sister chromatids are exchanged
Formation of new combinations of allels
