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Foundation (Cell cycle (G1 (Interval between end of cytokinesis and…
Foundation
Cell cycle
G1
Interval between end of cytokinesis and beginning of DNA replication. Non proliferating cells leave cell cycle here and enter G0
G1 checkpoint
- Is environment favourable?
Enter S phase
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M phase
-
- Are all chromosomes properly attached to mit spindle?
Pull duplicated chroms apart
G2
Preparations entry mitosis. Cell growth (protein synthesis) and completion of cellular products required to enter m phase
- Replication of DNA monitored, cells unable to divide if DNA damaged or mutated
G2 checkpoint:
- Is all DNA replicated?
- Is all DNA damage repaired- Enter M
Mitosis
M
Metaphase
- Chromosomes align: metaphase plate
Anaphase
- Centromeres divide
- Sister chromatids move to opp poles
- Sep sister chromatids: daughter chroms
Prometaphase
- Spindle fibres attach chromosomes: kinetochore
- Chromosomes condense
Telophase
- Nuclear membrane reforms
- Chromosomes decondense
- Spindle fibers disappear
Prophase
- Breakdown nuclear membrane + nucleolus
- Spindle fibres appear
- Chromosomes condense: two sister chroamatids held together by centromere
- Centrosome duplicates- opp ends cell: organize production microtubules: mit spindle
Cytokinesis
- Cytoplasm divides
- Parent cell becomes 2 daughter cells with identical genetic info
G2
- Cell double checks duplicated chroms for errors, making needed repairs
- Sister chromatids + centromere + loosely coiled replicated chroms
S
- Each of 46 chroms is duplicated by cell
G1
- Cellular contents, excluding chroms: replicated
Skin
- 15-20% body mass
- Protection from abrasion, chemicals and UV light
- Anti-microbial defense
- Thermoregulation
- Sensory function: contains variety of sensory receptors and nerves
- Two layers
- Hypodermis (subcutaneous tissue): liess deep to dermis, consists subcutaneous fat
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Dermis
Comprises meshwork of connective tissue: type 1 collagen fibers provide structural support, elastin fibers provide elasticity
Mast cells
- Involved in immune and inflammatory response
Macrophages and dendritic cells
- Carry out immune functions
Fibroblasts
- Synthesize and degrade connective tissue proteins
- Wound healing and scarring
Hair
- Composed primarily keratin from keratinocytes
- Base of each hair attached to erector pili (piloerector) muscle, contracts following sympathetic stimulation, each hair to stand erect
Sebaceous glands
- Produce sebum, lipid based secretion keeps skin moist and inhibits growth of certain bacteria
- Gland duct epties sebum directly into hair follicle, coating shaft and flowing onto epidermal surface
- Secretion rate increased by androgens and growth hormone and decreased by oestrogens
Sweat glands
- Apocrine sweat glands restricted to axillae and perineum. Activate in response to emotional stimuli. BO: apocrine glands
- Eccrine sweat glands: Widespread and secrete hypotonic fluid directly onto skin surface. Fluid evaporates, cools skin: thermoregulation
Meiosis
Females
Meiosis 1
Anaphase 1
- Chromosomes move to opp ends of cell as spindle fibers shorten
Telophase 1
- Chromosomes reach opp
- Nuclear membrane forms
Metaphase 1
- Spindle fivers attach chromosomes
- Chromosomes line up center of cell
-
Prophase 1
- Chromosomes begin condense
- Homologous chromosomes pair crossing over
- Recombinant chromosomes
Meiosis 2
Anaphase 2
- Centromeres divide + sister chromatids move to opp ends of cell as spindle fiber shortens
Telophase 2
- Chromosomes reach opp ends
- Nuc membrane forms
Metaphase 2
- Spindle fibers attach chromosomes
- Chromosomes line up center of cell
Cytokinesis
- Cell division
- 3 polar bodies and 1 mature egg cell
Prophase 2
- Chromosomes begin condense
- Nuclear membrane dissolves
- Spindle fibers form
Males
Meiosis 2
Anaphase 2
- Centromeres divide
- Sister chromatids move to opp ends of cells as spindle fibers shorten
Telophase 2
- Chromosomes reach opp ends
- Nuc membrane forms
Metaphase 2
- Spindle fibers attach chromosomes
- Chromosomes line up centre
-
Prophase 2
- Chromosomes condense
- Nuclear membrane dissolves
- Spindle fibers form
Meiosis 1
Anaphase 1
- Chroms start to move to opp ends of cell as spindle fibers shorten
Telophase 1
- Chroms reach opposite ends
- Nuclear membrane forms
Metaphase 1
- Spindle fibers attach chroms
- Chroms line up in center of cell
- Random assortment
-
Prophase 1
- Chromosomes begin condense
- Homologous chroms pair, crossing over occurs
- Recombinant chroms
DNA
Translation
- Occurs in cytoplasm, ribosome assembles around target mRNA
- tRNA attaches to start codon
- Each codon = specific amino acid
- tRNA bring specific amino acid that matches codo
- Ribosome translocates to next mrNA codon to continues process, creating AA
AA chain undergo further folding to become specific protein the gene codes for
Transcription
- occurs in nucleus of cell: segment DNA copied into RNA (mRNA) from one strand of DNA and free bases in nucleus by enzyme RNA polymerase
- Section of transcribed mRNA encode gene, mRNA will leave nucleus and meet with ribosome
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Y linked inheritance
- All affected males pass on their Y to all their sons, who will be affected
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Cell cycle
- Cell cycle is driven by cyclins:
- Proteins which activate cyclin dependent kinase enzymes
Fluid compartments
- Body water: 60% (more babies, less old)
- ICF: 2/3 body water
- ECF: 1/3 body water
- ECF interstitial fluid (3/4 ECF) and blood plasma (1/4 ECF)
- Different fluid compartments separate by partially permeable barriers: main goal: allow water move as freely as possible without causing unwanted movement of ions and proteins
- Movement of fluids to various compartments controlled by hydrostatic pressure (controlled by pumping pf heart) and osmotic pressure )controlled by soln conc)