Cell Cycle, Mitosis And Meiosis Flashcards
what are stem cell
unspecialised cells that retain the ability to become a wide variety of specialised cells
what is a specialised cell
as an organisms develops, cells differentiate to form different types of cells. Develop to let it to carry out a specific function. Include cells such as sperm, nerve & muscle cells
the three types of stem cells are?
totipotent are stem cells with the potential to differentiate into any type of cell
multipotent cell with limited potential to develop into many types of differentiated cells
Pluripotent cells that are capable of developing into most, but not all of the body’s cell types.
what is haploid, diploid, homologous chromosomes, somatic cells, gametes, gene and locus.
- An organisms or cell having only one complete set of chromosomes
- an organisms or cell having two sets of chromosomes
- Pair of chromosomes that are the same size
- Body cells
- a mature haploid male or female germ cell that is able to unite with another of the opposite sex in sexual reproduction to form a zygote
- A segment of DNA on a chromosomes that codes for a particular polypeptide
- location of a gene on a chromosomes
cell cycle
- is a series of events that cells go through as they grow and divide
G1 phase- stage of interphase in which cell grows and performs its normal functions; releases energy and protein synthesis
S phase- The synthesis phase of the cell cycle; the portion of interphase during which DNA is replicated
G2 phase - stage of interphase in which cell duplicates its organelles
cell cycle checkpoints - mechanisms that monitor the preparedness of a eukaryotic cell to advance through the various cell cycle stages
alleles - different forms of a gene
sister chromatids - identical copies of a chromosomes; full sets of these are created during the S subphrase of interphase
centromere- area where the chromatids of a chromosomes are attached
bivalent- a pair of homologous chromosomes
what is mitosis, uses and stages
- cell division in which the nucleus divides into nuclei containing the same number of chromosomes. two genetically identical daughter cells are produced
it is used for growth, repair and asexual reproduction
1. Prophase: chromosomes condense & become visible, nuclear envelope dissolves
2.Metaphase: Chromosomes line up in the middle of the cell. Spindle fibres start to form
3. Anaphase: Sister chromatids separate and move to opposite ends of the cell
4. Telophase: Chromosomes unwind, nucleus starts to reform
5. Cytokinesis- division of the cytoplasm
what is meiosis, where it occurs, variation and fertilisation
- nuclear division that produces gametes, 4 genetically different haploid daughter cells are produced. there are two nuclear divisions
- testes and ovaries
- crossing over and independent assortment
-When two haploid gametes fuse the diploid chromosomes number is restored. This ensures that in sexual reproduction fusion of haploid gametes restore the original chromosomes number (diploid) and that chromosome numbers are kept constant.
stages of meiosis
meiosis 1: homologous chromosomes separate
meiosis 2: sister chromatids separate
crossing over: process in which homologous chromosomes exchange portions of their chromatids during meiosis
Prophase1: Chromosomes become visible; nuclear envelope breaks down; crossing-over occurs
independent assortment: independent segregation of genes during the formation of gametes
metaphase1: paired homologous chromosomes line up across the center of the cell
anaphase 1 : homologous chromosomes separate
telophase 1 ( meiosis): a nuclear membrane forms around each cluster of chromosomes
Prophase 2: A new spindle forms around the chromosomes
metaphase 2: Centromeres of chromosomes line up randomly at the equator of each cell
anaphase 2: sister chromatids separate
telophase 2: a nuclear membrane forms around the chromosomes in each of the 4 new cells
