chapter 2 - nucleic acids and proteins

Question 1

what are nucleotides made up of?

Answer 1

• Phosphate group(s)
• Pentose (5 carbon) sugar (deoxyribose: DNA, ribose: RNA)
• Nitrogenous base (A, C, G, T/U)

Question 1

what are nucleic acids?

Answer 1

• organic biomacromolecules
• polymers of nucleotides

Question 2

what are the two types of nucleic acids?

Answer 2

DNA (deoxyribonucleic acid)

RNA (ribonucleic acid)

Question 3

polymer

Answer 3

a large molecule made up of a repeating chain of subunits of monomers

Question 4

monomer

Answer 4

a molecule that can be bonded to other identical molecules to form a polymer

Question 5

what is the structure of RNA?

Answer 5

• 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

Question 6

what is RNA polymerisation?

Answer 6

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

Question 7

what is the structure of DNA?

Answer 7

• Two strands of multiple nucleotide chains run antiparallel
• contains deoxyribose sugar
• H bonds form between complementary nitrogenous bases
  (A-T) (C-G)

Question 8

what is DNA polymerisation?

Answer 8

DNA polymerase enzyme uses deoxynucleotides (same process as RNA polymerisation)

Question 9

what is the double helix?

Answer 9

the DNA molecule naturally spirals, making a complete right handed twist for every 10.5 base pairs

Question 10

what is mRNA

Answer 10

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

Question 11

what is tRNA

Answer 11

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

Question 12

what is rRNA

Answer 12

ribosomal RNA
- makes up 60% of the structure of ribosomes

Question 13

what do nucleotides, amino acids, and fatty acids make up respectively?

Answer 13

nucleic acids (DNA + RNA), proteins, and triglycerides

Question 14

what is a phosphodiester bond?

Answer 14

the bond that holds together the phosphate group of one molecule to the 3’ carbon of another

Question 15

what are the features of DNA?

Answer 15

• prime ends are always opposite (5’, 3’ - 3’, 5’)
• one less hydroxyl group on the 2’ (deoxy)
• every 3 nucleotides are triplets

Question 16

what are amino acids

Answer 16

molecules that combine to form proteins

Question 17

what is a polypeptide?

Answer 17

a chain of amino acids

Question 18

what is the central dogma of molecular biology?

Answer 18

genetic info can flow from nucleic acid to nucleic acid/protein, but not protein to nucleic acid.

Question 19

what are genes?

Answer 19

lengths of DNA that code for the making of a gene product, often a polypeptide.

Question 20

upstream

Answer 20

towards 5’ UTR
(leader in prokaryotic cells)

Question 21

downstream

Answer 21

towards 3’ UTR
(trailer in prokaryotic cells)

Question 22

what are introns?

Answer 22

transcribed (non-coding) regions of a gene that are removed from the transcript (RNA) before translation.

• stays within nucleus
• not found in prokaryotic cells

Question 23

what are exons?

Answer 23

transcribed (coding) regions of a gene that are translated.

contain the coding instructions for joining amino acids, which are expressed

Question 24

what is a terminator?

Answer 24

genetic parts that usually occur at the end of a gene or operon and cause transcription to stop

Question 25

transcription factor

Answer 25

a protein that controls the rate of transcription

Question 26

promoter region

Answer 26

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)

Question 27

operator region

Answer 27

the region of the DNA where the repressor molecule attaches to inhibit transcription. (specific to prokaryotic gene regulation)

Question 28

repressor

Answer 28

a type of regulatory protein that inhibits gene transcription in prokaryotic cells, hence inhibiting gene expression

Question 29

activator

Answer 29

a type of regulatory protein that increases the rate of transcription

Question 30

enhancer

Answer 30

increase gene expression. increase in RNA polymerase to the gene's promoter increases rate of transcription.

Question 31

silencer

Answer 31

prevent/reduce (repressing or silencing) the transcription of genes.

Question 32

what is transcription?

Answer 32

RNA polymerase transcribing DNA into mRNA, so the genetic code can be sent to ribosomes to make proteins

Question 33

UTR

Answer 33

untranslated region

Question 34

what does it mean by 'universal'

Answer 34

nearly all living organisms use the same codons to code for specific amino acids

Question 35

unambiguous

Answer 35

Each codon is only capable of coding for one specific amino acid (UUA --> leucine)

Question 36

degenerate

Answer 36

amino acids may be coded by multiple different codons

Question 37

non-overlapping

Answer 37

each triplet/codon is read independently, without overlapping from adjacent triplets/codons. L --> R, read in triplets

Question 38

start triplet

Answer 38

where RNA polymerase begins to copy the gene into a mRNA molecule (AUG)

Question 39

template strand

Answer 39

the strand to be copied (3’ --> 5’)

Question 40

termination sequence

Answer 40

codes for the termination of transcription

Question 41

operon

Answer 41

a functioning unit of DNA containing a cluster of genes under the control of a single promoter

Question 42

genome

Answer 42

collection of genes

Question 43

proteome

Answer 43

collection of proteins

Question 44

which bases are pyrimidines

Answer 44

cytosine, uracil, thymine (CUT)

Question 45

which bases are purines

Answer 45

guanine and adenine