Cellular Replication: Division, Cycle, DNA, RNA, Protein Synthesis Flashcards
What can increased cell proliferation be caused by ?
- shortening the cell cycle
- recruiting quiescent (sleeping) cells to divide & proliferate
What are different cell types?
- Labile cells
- stable cells
- non-dividing (permanent) cells
What are labile cells?
- Constantly dividing, regenerate rapidly e.g. Surface epithelium
What are stable cells?
- Low level of replicative activity but can rapidly divide in response to stimuli e.g. Liver damage
What are non dividing cells?
-Terminally differentiated , unable to proliferate (neurons)
What has increased proliferation & decreased proliferation?
- Increased proliferation: cancer
- decreased proliferation: chronic wound
What are the main events of the cell cycle?
- Interphase
- mitosis
- cytokinesis: cytoplasm division
What are the phases of interphase?
- G 1: sure environment is correct e.g. O2, nutrients, phase before synthesis of DNA
- s phase: synthesis, nuclear DNA is synthesised, chromosomes are duplicated
-G2: after DNA synthesis is complete, lasts until mitosis. Makes sure duplicated DNA is correct for mitosis
What are the main stages of mitosis?
- Prophase: centrioles move to poles
2, prometaphase: microtubules attach to chromosomes - Metaphase: chromosomes align nuclei disappear
4.anaphase: chromosomes divide and move to poles - Telophase: nuclear membrane reappears and cytokinesis occurs
What different Cyclins are required for which parts of the cell cycle?
- Cyclin D: for Go and G1
- Cyclin A: for S phase and G2
-Cyclin B: for mitosis
What is the cyclin/cdk action?
- CDK protein is always present but its active site isn’t exposed - cyclin protein is only made at a certain point of the cycle
- Cyclin binds to CDK exposing its active site
- A protein substrate and ATP binds to CDK, The protein substrate is phosphorylated
- The phosphorylated protein regulates the cell cycle. Each CDK has different protein targets
What are some characteristics of DNA?
-deoxyribonucleic acid
- base pairs, phosphate / deoxyribose sugar
Instructions needed for an organism to develop, survive & reproduce
- double stranded
What are some characteristics of RNA?
- Ribonuleic acid
-base pairs, phosphate, ribose sugar - protein synthesis
-Single strand
What are the different types of RNA?
- Messenger RNA
- transfer RNA
- ribosomal RNA
What are the components of a nucleotide?
- phosphate group
- pentose sugar
- nitrogenous base
What are the purine bases?
-Adenine
- guanine
What are pyrimidine bases?
- Uracil
-Cytosine - thymine
What are the differences between RNA & DNA?
- RNA has uracil while DNA contains thymine
-RNA contains ribose and DNA contains deoxyribose - DNA is double stranded
How do nucleotides join and the base pairs?
- Phosphodiester bonds
- 5’, 3’ by DNA polymerase
- Between A & T (2 hydrogen bonds)
- Between C & G (3 hydrogen bonds)
What are chromosomes?
- Thread like structures inside the nucleus
- Human body contains 46 chromosomes (23 pairs)
- Each section of a chromosome contains the code for the production of a gene (section of polypeptide chain that codes for a protein)
What is DNA helicase and polymerase?
- DNA Helicase: separate double stranded DNA into single strands
- DNA Polymerase: Contain 5 types: a, B, Y, 5, E (don’t exactly look like these symbols) add nucleotides
What is Transcription?
- Initiation
- Before start of gene to be coded = promoter
- Need transcription factors
What are the units in a Ribosome?
- 2 units, 1 small and 1 large
- Large unit has 3 subunits:
- A-site (amino acyl) accepts incoming amino acids. Joins the ribosome
- P-site (peptide) peptide is made
- E-site (Exit) holds the tRNA before it leaves the ribosome
What are the happens when the ribosome reaches the stop codon in translation?
- When a ribosome reaches a stop codon on mRNA, the A site on the ribosome accepts a protein called release factor instead of tRNA
- The release factor hydrolyses the bond between the tRNA in the P-site and the last amino acid. Polypeptide is freed from ribosome
- 2 ribosomal subunits and the other components of the assembly dissociate
