U1T6 - Keywords Flashcards
Cell Cycle
The cycle of growth + division of a cell. Formation of new cells + contents, growth, mitosis + dividing into 2.
Mitosis
1 cell division where 2 daughter cells are produced with same number of chromosomes as parent cell. Genetically identical. Only a part of the cell cycle. Nuclear division following DNA replication during S phase. Parent cell = haploid/diploid. Homologous chromosomes don’t associate during prophase. No chiasmata. Asexual reproduction. Occurs in all organisms.
Cytokinesis (Mitosis)
When the cell physically divides into 2 at the end of mitosis forming 2 genetically identical daughter cells, each with an identical chromosome makeup to parent cell. Division of cytoplasm.
G
S
Gap Phase
Synthesis Phase
Interphase
Longest part of cell cycle. e.g. human embryo development = 24 hours.
G1 Phase
Gap/Growth Phase. Period of rapid cell growth when new organelles are synthesised.
S Phase
Synthesis of new DNA, DNA in cell doubles, chromosomes replicate.
G2 Phase
Gap/Growth Phase. Centrioles replicate + microtubules start to construct spindle. ATP stores built up.
G0 Phase
Point where cell is resting in unfavourable conditions. Can last days, weeks or years. Still does normal processes.
Apoptosis
When a cell is destroyed at a cell cycle checkpoint if growth phases haven’t been carried out properly.
Cancer
Cell division which is out of control.
Prophase (Mitosis)
Longest stage in mitosis. Chromatin in nucleus becomes shorter + thicker, it has become condensed + visible. It has more strength, preventing damage during mitosis.
Metaphase (Mitosis)
Short phase. 2 Chromatids move towards cell equator. Attach themselves to microtubules of spindle fibre by centromere.
Anaphase (Mitosis)
Short phase. Centromeres which hold each pair of chromatids together divide. Chromatids move to poles, centromere first by spindle fibres contracting. As they contract, they shorten + pull chromatids apart to opposite ends of the cell.
Telophase (Mitosis)
Sister chromatids end at opposite poles of cell + become chromosomes which decondense + become less visible. Nucleolus reappears + nuclear membrane reforms around 2 chromosome groups. Spindle disappears + there are now 2 distinct nuclei.
Mitotic Poison
Drug which inhibit microtubule formation which are structures that make up cell spindle which moves + separates chromatids, therefore inhibiting cell division at M phase of cell cycle.
Metastasize
Grow + spread throughout the body.
Antimetabolites
Chemical that inhibits the use of a metabolite which is a chemical that’s part of animal metabolism. Some of first effective chemotherapeutic agents discovered. Made up of folic acid, pyrimidine or purine chemicals. Have similar structures to naturally occurring molecules used in nucleic acid of DNA/RNA synthesis.
Nucleosome
Length of DNA double helix containing 200 base pairs wound around a bead of histone protein.
Chromosomes
Structures which provide continuity between each cell generation. Made of DNA. Only seen when cell is dividing.
Karyotype/karyogram
Photomicrograph which shows the number + appearance of chromosomes in a cell.
Diploid
Chromosomes are arranged in pairs within their cells. 2 copies of each chromosome (2n)
Homologous Pairs
Diploid cells which have chromosomes arranged in pairs within their cells. Maternal + paternal chromosomes paired. Identical in gene context + order.
Allele
When chromosomes of a homologous pair contain the same gene in a different form e.g. blue eyes + green eyes/dominant + recessive.
Meiosis
Type of cell division which produces gametes with haploid chromosomes so a diploid zygote is produced at fertilisation. It is a reduction division. 2 cell divisions. daughter cells. Parent cell = diploid. Bivalents formed form homologous chromosomes pairing. Chiasmata form between chromatids of homologous chromosomes during prophase I. Daughter cells genetically different. Occurs in animals + plants.
Zygote
Fertilised egg.