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Describe the structure of DNA
- Phosphoric acid and deoxyribose sugar form backbone of DNA. An organic base of ACG or T is added. Draw a diagram of a phosphate with a 5' position after it and a 3' position before the sugar.
- 10 base pairs per turn. 2 chains held together by hydrogen bonds. Chains run in opp polarity. Bases point in. flat planes perp to axis of helix.
What is a nucleotide
DNA backbone with one base
What are the 4 bases and how do they bind
Adenine(purine), cytosine(pyrimi.), guanine(purine), Thymine(pyrimidine)
What is a histone
Proteins that wrap round DNA twice. Proteins that coil and fold chromosome molecule into a condensed state. It is the core of the nucleosome.
What is Chromatin
Chromatin is a series of nucleosome’s. Exist in interphase only.
What is a nucleosome
An octamer histone plus the linker DNA of 147 bp.
What are telomeres
- Telomeres are repetitive DNA sequences located at the termini of linear chromosomes of most eukaryotic organisms.
- Telomeres compensate for incomplete semi-conservative DNA replication at chromosomal ends.
What are chromosomes
Highest level of packaged DNA. Chromosomes appear during cell division
What is transcription
Transcription is the formation of RNA from DNA under the influence of RNA-polymerase.
What is translation
Translation is the formation of peptide from mRNA in the ribosome.
What is endoplasmic reticulum
- Network of membranes extending envelope and is found spread to much of the cell.
- RER is rough because of ribosomes
- RER is flattened sheets.
- SER is more tubular.
- Space between sheets and inner tubes = ER matrix.
- SER = extension of RER
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