7. Nucleic acids Flashcards
What are the functions of DNA primase and DNA polymerase 1 in DNA replication?
DNA primase: adds short RNA primer to template strands
DNA Polymerase 1: replaces RNA primers with DNA
Some genes do not code for proteins. T/F?
F. All genes code for proteins.
Promoters are transcribed along with the gene. T/F?
T
Introns are only found within genes coding for proteins. T/F?
F
DNA has regions that do not code for proteins. State two functions of these regions.
Promoters/operators regulate gene expression
telomeres give protection to the end of chromosomes (during cell division)
genes for tRNA/mRNA production
What strand does RNA polymerase bind to initiate transcription?
The antisense strand is the template DNA strand which is transcribed. The sense strand is the DNA strand which has the same base sequence as the mRNA with thymine instead or uracil.
Outline the structure and functions of nucleosomes. (4)
found in eukaryotes consists of DNA wrapped around histones Histones are in an octamer, which is two set copies of four histones in linker region supercoil chromosomes regulate gene expression
What does methylation of DNA do?
Inhibits transcription
Binding of DNA more tightly to histone so less accessible to transcription factors
What does acetylation of DNA do?
Promote transcription.
Binding of DNA more loosely to histone so more accessible to transcription factors
Where are proteins synthesized by free ribosomes used?
within the cell
Where are proteins synthesized by bound ribosomes used?
secretion/use in lysosomes
Describe the primary structure of protein
sequence of amino acids
Formed by covalent peptide bonds between adjacent amino acids
Describe the secondary structure of protein
Held together by hydrogen bonds between (non-adjacent) amine (N-H) and carboxylic (C-O) groups
alpha helices and beta pleated sheets stabilized by hydrogen bonding
fibrous protein
Describe the tertiary structure of protein
Further folding of the polypeptide stabilized by interactions between R groups
ionic bond
hydrophobic and hydrophilic amino acids
disulphide bridges
hydrogen bond
Gives 3D globular shape/ shape of active site
Describe the quartenary structure of protein
interaction between multiple polypeptides
Fibrous and Globular proteins
Example: hemoglobin
