A1 Cell Cycle Flashcards
How many stages of the cell cycle are there?
3.
What are the three stages of the cell cycle?
Interphase, mitosis and cytokinesis
What is the cell cycle?
The sequence of events that take place in a cell to prepare for cell divison
What is interphase and its three phases?
The phase of the cell cycle in which the cell is preparing for divison
G1, S and G2
What happens during G1?
Cell grows and increases in size, protein synthesis and energy is released
What is mitosis and what happens during it?
Cell division in which the nucleus divides into nuclei containing the same number of chromosomes, two genetically identical daughter cells are produced
What happens during G2?
A stage of interphase where the cell continues to grow and replicate organelles.
What happens during S phase?
The synthesis phase of the cell cycle; the portion of interphase during which DNA is replicated
What is cytokinesis?
The division of cytoplasm and organelles to produce two genetically identical daughter cells
What is cell potency?
A stem cell’s ability to differentiate specialised cell types.
What are three types of potency levels?
Totipotent, pluripotent and multipotent
What are totipotent cells?
Cells that can develop into any cell type including the placenta. They have a very high potency.
What is a haploid?
A organism or cell that has only one complete set of chromosomes
What is a diploid?
An organism or cell that has two sets of chromosomes
What is a somatic cell?
A cell in the body which is not a gamete or undifferentiated cell
What is a pluripotent cell?
Cells that can develop into any cell type not the placenta. It has a low potency.
What is a multipotent cell?
Cells that can develop into multiple but limited cell types. They have a low potency.
What are unipotent cells?
Cells that can only develop into one cell type
What is a gamete?
A mature haploid male or female germ cell that is able to unite with another of the opposite sex in a sexual reproduction to form a zygote
What is a gene?
A segment of DNA on a chromosome that codes for a particular polypeptide
What is a locus?
Location of a gene on a chromosome
What happens during cell cycle checkpoints and what is it?
Mechanisms that monitor the preparedness of a eukaryotic cell to advance through the various cell cycle stages
What is a centromere?
An area where the chromatids of a chromosome are attached
What are sister chromatids and what part of the cell cycle are they made?
Identical copies of a chromosome; full sets of these are created during the S sub-phase of interphase
What does it mean when chromosomes are bivalent?
A pair of homologous chromosomes
What does mitosis use?
Growth, repair and asexual reproduction
What are the stages of mitosis?
Prophase, metaphase, anaphase and telophase (PMAT)
What happens during prophase?
Chromosomes condense and become visible, nuclear envelope dissolves
What happens during metaphase?
Chromosomes line up in the middle of the cell. Spindle fibres start to form.
What happens during anaphase?
Sister chromatids separate and move to opposite ends of the cell
What happens during telophase?
Chromosomes unwind and the nucleus starts to reform
What is meiosis and what happens during it?
Nuclear division that produces gametes, 4 genetically different haploid daughter cells are produced. There are two nuclear divisions.
Where does meiosis occur?
It occurs in the testes and ovaries
How is variation achieved in meiosis?
Crossing over, random assortment and random fusion
What happens during fertilisation and what does it ensure?
When two haploid gametes fuse the diploid chromosome number is restored. This ensures that in sexual reproduction fusion of haploid gametes restore the original chromosome number (diploid) and that chromosome numbers are kept constant
What are the stages of meiosis?
Meiosis 1, meiosis 2, crossing over, prophase 1, independent assortment, metaphase 1, anaphase 1, telophase 1, prophase 2, metaphase 2, anaphase 2 and telophase 2
Give 3 examples of differences between mitosis and meiosis
Mitosis has one nuclear division, meiosis has 2 nuclear divisions
Mitosis is used for growth and repair and meiosis for the production of gametes
Meiosis has crossing over and independent segregation which occurs in meiosis 1 and mitosis has no crossing over or independent segregation
