Genetic role of protein synthesis, cell functiona and cell production Flashcards
What are the building blocks of DNA?
1) phosphoric acid
2) deoxyribose sugar
3) nitrogenous bases
- purine; adenine and guanine
- pyrimidine; thyamine and cytosine,
Which nitrogenous base bind to which?
A-T and G-C or U-A in RNA
How does RNA differ from DNA
Ribose instead of deoxyribse and thymine is replaced by uracil
What are the 4 steps in transcription?
1) RNA polymerase bonds to the promoter region DNA
2) Causes unwinding of the DNA helix
3) Adds RNA nucleotides together
4) RNA polymerase dislodges when it reaches the chain terminating region
What are the 3 tyes of RNA and their role?
mRNA; carries genetic code to the cytoplasm from the nucleus
tRNA; transports activated aa to the ribosomes to be used in assembling proteins. This contains codons and anticodons in the mRNA-> this allows them to transfer the correct aa to the ribosome
rRNA; along with proteins this forms he ribosomes. rRNA makes up 60% of the ribosome. Alwasys functions in conjunction with tRNA and mRNA
what are polyribosomes?
clusters of ribosomes that can attach to the mRNA at the same time.
what is an operon?
cluster of genetic material containing genes and is under control of a regulatory signal or promoter
what is a promoter and a repressor operator ?
promoter lies upstream from the operon and is what the RNA polymerase binds to. Repressor operator lies in the middle of an operon and can bind to a repressor protein which inhibits the transcription.
What is the role of chromosomes and histones?
DNA is wrapped around histones and which makes chromosomes. This allows a tight packaging of vast amounts of DNA, and when packaged, the DNA is unreadable
what is interphase?
the period in which DNA replication has occurred and normal cell functions occur
What is a centromere?
The DNA replicates prior to mitosis to form two chromatids held together by a centromere.
What are the 5 steps of mitosis?
1) Prophase - chromosomes become condensed
2) prometapahse - te mitotic apparatus punctures the nuclear cytoplasm and vinds to centromeres
3) metaphase - the chromatids line up in the middle
4) anaphase - the chromatids are pulled apart and pulled to the ends of the cell
5) telophase - nuclear membranes form around the chromatids and cell splits
Why do most defective nucleated cells NOT form cancer?
1) less survivability than normal cells
2) normal cell suicide pathways in normal cells are still functional despite mutations
3) immune system kills the cell
4) several oncogenes need to be activated to form a line
What are the factors which increase the risk of mutations?
1) ionizing radiation
2) heredity
3) viruses (retroviruses)
4) physical irritants
5) chemical substances
