The Cell Cycle Flashcards
What is the cell cycle
Is the process that all body cells use to grow and divide. There are two phases interphase and mitotic phase.
What are the functions of the cell cycle
- Growth of organisms
- Repair of body tissue
- Asexual reproduction
- Replacement of worn out/damaged cells
What are the products of the cell cycle
Two genetically identical daughter cells
Interphase stages
G1- synthesis of proteins, organelles replicate, cells increase in size
S- replication of each chromosome
G2- cells continue to grow in size, duplicated DNA is checked for errors and energy stores increase.
What is the mitotic phase
Mitosis and cytokinesis
Stages of mitosis
Prophase
Metaphase
Anaphase
Telophase
What is prophase
- chromosomes condense and thicken forming sister chromatids.
- centrioles go to opposite poles of the cell and spindle fibres attach to the centromeres
- nuclear envelopes disappear
what is Metaphase
-Chromosomes are aligned in the centre by spindle fibres at the equator
what is Anaphase
-centromere divide and chromatids separate form each other by spindle fibres. They are pulled to opposite poles.
what is Telophase
Chromatids uncoil becoming long and thin, they are now chromosomes. A nuclear envelope reforms around chromosomes.
what is Cytokinesis
Where the cytoplasm divides and two genetically identical daughter cells are formed.
What g0
When the cell leaves the cell cycle due to the cell being damaged.
What is Meiosis
When 4 daughter haploid cells are formed which are genetically different due to the process of crossing over and independent assortment.
Prophase 1 for meiosis
Homologous chromosomes pair up forming bivalentes. They are brought together as a result of chromatids entangling. This is called crossing over.
what happens at Metaphase 1
Homologous pairs of chromosomes assemble along the equator. The orientation is random and paternal or maternal could face either direction. This is called independent assortment. Allowing different combinations of variations of alleles.
what happens at Anaphase 1
Homologous proteins are pulled to opposite poles and chromatids stay joined. Sections of DNA on sister chromatids break off and exchange DNA. This is chiasmata.
what happens at Telophase
Chromosome assemble at each pole and a nuclear membrane reforms.
what happens at Prophase 2
Chromosomes consist of 2 chromatids and condense. The nuclear envelope breaks down and spindle formation begins.
what happens at Metaphase 2
Individual chromosomes line up on the equator.
what happens at Anaphase 2
Chromatids of different chromosome are pulled to opposite pole after division of centromeres
what happens at Telophase 2
Chromatids assemble at the poles. The chromosomes uncoil and form chromatin. Nuclear envelope reforms. Cytokinesis happens.
What is homologous chromosome
Are chromosomes one from each parent. They have the same genes but different alleles
What happens if a damaged DNA is discovered at G2
They cell cycle is halted and the cell tries to repair the DNA.
