Topic 7 Flashcards
Eukaryotic cellular growth, genetic diversity & inheritance (34 cards)
What is the concept of cell lifespan for stem cells, neurons, memory T cells, oocytes, red blood cells, gastric epithelial & skin cells, neutrophils
Stem cells: lifetime
Neurons: decades
Memory T-cells: years - decades
Oocytes: decades
Red blood cells: 4 months
Gastric epithelial & skin cells: few datys
Neutrophils: few days (<8 in circulation)
How do cells divide?
Divide by the process of mitosis
Overview of cell cycle?
- Interphase - G1 (Gap 1): synthesis of proteins and organelles, 8-10 hrs
- Interphase - S phase (synthesis): DNA replication, 2nd set of DNA made to prepare for cell division, short phase 5 hrs
- Interphase - G2: DNA repair (check for errors), prepare for mitosis (cell growth & protein syn.), 4-6 hrs
- Mitosis & cytokinesis: nuclear division => 5 stages, last phase overlaps w/cytoplasm division (cytokin), production of 2 genetically identical daughter cells, 30-45 mins
What are the factors that limit eukaryotic cell growth?
SA:V ratio - ability to exchange w/ environment
What are the major steps in mitosis?
Interphase (G1, S phase, G2) 2. Prophase from each other 3. Prometaphase 4. Metaphase - align of condensed chrom. along metaphase plate - equal distance between 2 poles 5. Anaphase - Ana. A - Ana. B 6. Telophase & cytokinesis
What occur in prophase in mitosis?
- spindle fibres move & microtubules between
- condensed chrome.
- 👭 chromatids attach to each other
- centrosomes migrate away from each other
What occur in pro-metaphase in mitosis?
- fragmentation of nuclear membrane
- spindle microtubules attach to chromatids @ centromere
What occur in metaphase in mitosis?
- align of condensed chrom. along metaphase plate
- equal distance between 2 poles
What occur in anaphase in mitosis?
Ana. A:
- Chrom. pulled towards poles via centromere Ana. B:
- spindle fibres move away from away from each other
What occur in telophase and cytokinesis in mitosis?
TELOPHASE:
- daughter chrom. reach spindle poles
- nuclear envelope form around daughter cells
- interphase chromatin structure resumes
- spindle disassembles
- simultaneously w/cytokinesis
CYTOKINESIS:
- 2nd process in mitotic cell division
- separates cytoplasm
- cleavage furrow forms by actin along spindle equator
What are the features of cells produced by mitotic division?
1 parent cell produces 2 genetically identical daughter cells
What are the consequences if errors in mitosis?
- mutation carried by subsequent generations => cancer
- no genetic diversity
What is the process of meiosis?
Meiosis I: 1. Prophase I 2. Metaphase I 3. Anaphase I 4. Telophase I & cytokinesis Meiosis II: no DNA rep. - 1/2 # chrom. present 5. Prophase II 6. Metaphase II 7. Anaphase II 8. Telophase II
What occurs in prophase I of meiosis I?
- homologous chrom. pair - process of synapsis forms bivalent
- CROSSING OVER OCCURS
- synaptonemal complex appears @ beginning & disappears after crossing over
- nuclear envelope fragments
- synpatonemal complex
What occurs in metaphase I of meiosis I?
paired homologous chrom. align @ equator
What occurs in anaphase I of meiosis I?
👭 chromatids chrom. move together to spindle poles
What occurs in telophase I and cytokinesis of meiosis I?
2 daughter cells produced
Telophase:
- daughter chrom. reach spindle poles
- nuclear envelope form around daughter cells
- interphase chromatin structure resumes
- spindle disassembles
- simultaneously w/cytokinesis
Cytokinesis:
- 2nd process in mitotic cell division
- separates cytoplasm
- cleavage furrow forms by actin along spindle equator
What occurs in telophase II of meiosis II?
- production of 4 haploid cells
- 👭 chromatids separate e
Define and describe autosomal recessive.
- 2 copies of the mutant must be present in non-sex chromosomes (chromosomes 1-22) for trait
- can skip generations
Define and describe autosomal dominant.
- 1 copy of a mutant gene and one normal gene on a pair of autosomal (non-sex) chromosomes
- no generations skip
Define and describe sex-linked recessive.
- allele on x-chromosome (#23)
- males affected one x chromosome
- females only require 2 copies of alleles (less likely to be affected)
In what kind of cells does meiosis occur?
- occur in germ-line cells (sex cells)
- produces haploid cells (1/2 # chroms)
What are the features of cells produced by meiotic division?
produces 4 daughter cells that are different to parent and to each other
How are new combinations of genes produced in every generation?
- during fertilization, a gamete (haploid) from each parent combine to form a zygote (diploid)
- due to recombination & independent assortment in meiosis, each gamete contains a different set of DNA
- produces unique combination of genes in the resulting zygote
