chapter 2 - nucleic acids and proteins Flashcards
what are nucleotides made up of?
- Phosphate group(s)
- Pentose (5 carbon) sugar (deoxyribose: DNA, ribose: RNA)
- Nitrogenous base (A, C, G, T/U)
what are nucleic acids?
- organic biomacromolecules
- polymers of nucleotides
what are the two types of nucleic acids?
DNA (deoxyribonucleic acid)
RNA (ribonucleic acid)
polymer
a large molecule made up of a repeating chain of subunits of monomers
monomer
a molecule that can be bonded to other identical molecules to form a polymer
what is the structure of RNA?
- Ribonucleic acid
- Single stranded nucleic acid containing ribose sugar
- Thymine is replaced by Uracil which pairs with Adenine
Three types of RNA:
mRNA
tRNA
rRNA
what is RNA polymerisation?
RNA is built by RNA polymerase enzyme.
Adds new nucleotides in a 5’ to 3’ direction (adds to 3’ end)
- is a condensation polymerisation reaction, where a diphosphate is produced than H2O
what is the structure of DNA?
- Two strands of multiple nucleotide chains run antiparallel
- contains deoxyribose sugar
- H bonds form between complementary nitrogenous bases
(A-T) (C-G)
what is DNA polymerisation?
DNA polymerase enzyme uses deoxynucleotides (same process as RNA polymerisation)
what is the double helix?
the DNA molecule naturally spirals, making a complete right handed twist for every 10.5 base pairs
what is mRNA
messenger RNA
- forms in nucleus through transcription
- Carries a copy of the genetic code from DNA in the nucleus to the ribosome for protein synthesis
– every 3 nucleotides are codons
what is tRNA
transfer RNA
- Carries amino acids from the cell cytoplasm to the ribosome, and pairs with the complementary code carried by the mRNA
– every 3 nucleotides are anticodons
what is rRNA
ribosomal RNA
- makes up 60% of the structure of ribosomes
what do nucleotides, amino acids, and fatty acids make up respectively?
nucleic acids (DNA + RNA), proteins, and triglycerides
what is a phosphodiester bond?
the bond that holds together the phosphate group of one molecule to the 3’ carbon of another
what are the features of DNA?
- prime ends are always opposite (5’, 3’ - 3’, 5’)
- one less hydroxyl group on the 2’ (deoxy)
- every 3 nucleotides are triplets
what are amino acids
molecules that combine to form proteins
what is a polypeptide?
a chain of amino acids
what is the central dogma of molecular biology?
genetic info can flow from nucleic acid to nucleic acid/protein, but not protein to nucleic acid.
what are genes?
lengths of DNA that code for the making of a gene product, often a polypeptide.
upstream
towards 5’ UTR
(leader in prokaryotic cells)
downstream
towards 3’ UTR
(trailer in prokaryotic cells)
what are introns?
transcribed (non-coding) regions of a gene that are removed from the transcript (RNA) before translation.
- stays within nucleus
- not found in prokaryotic cells
what are exons?
transcribed (coding) regions of a gene that are translated.
contain the coding instructions for joining amino acids, which are expressed
what is a terminator?
genetic parts that usually occur at the end of a gene or operon and cause transcription to stop
transcription factor
a protein that controls the rate of transcription
promoter region
a region of DNA upstream of a gene to be copied, where proteins such as RNA polymerase and transcription factors bind to initiate transcription.
(TATA box)
operator region
the region of the DNA where the repressor molecule attaches to inhibit transcription.
(specific to prokaryotic gene regulation)
repressor
a type of regulatory protein that inhibits gene transcription in prokaryotic cells, hence inhibiting gene expression
activator
a type of regulatory protein that increases the rate of transcription
enhancer
increase gene expression.
increase in RNA polymerase to the gene’s promoter increases rate of transcription.
silencer
prevent/reduce (repressing or silencing) the transcription of genes.
what is transcription?
RNA polymerase transcribing DNA into mRNA, so the genetic code can be sent to ribosomes to make proteins
UTR
untranslated region
what does it mean by ‘universal’
nearly all living organisms use the same codons to code for specific amino acids
unambiguous
Each codon is only capable of coding for one specific amino acid (UUA –> leucine)
degenerate
amino acids may be coded by multiple different codons
non-overlapping
each triplet/codon is read independently, without overlapping from adjacent triplets/codons.
L –> R, read in triplets
start triplet
where RNA polymerase begins to copy the gene into a mRNA molecule (AUG)
template strand
the strand to be copied (3’ –> 5’)
termination sequence
codes for the termination of transcription
operon
a functioning unit of DNA containing a cluster of genes under the control of a single promoter
genome
collection of genes
proteome
collection of proteins
which bases are pyrimidines
cytosine, uracil, thymine (CUT)
which bases are purines
guanine and adenine
