DNA transcription and translation

Question 1

what is the genotype of an organism?

Answer 1

the alleles it has for each of its genes, determined by the sequences of bases in its DNA

Question 2

what is the phenotype of an organism?

Answer 2

its displayed traits

Question 3

what is the structure of a nucleotide?

Answer 3

a phosphate group, a pentose sugar and a nitrogen-containing base

Question 4

where is the ester bond found in a nucleotide?

Answer 4

between the phosphate and the sugar

Question 5

where is the glycosidic bond found in a nucleotide?

Answer 5

between the sugar and the base

Question 6

what are the five types of DNA base?

Answer 6

adenine, guanine, cytosine, thymine and uracil

Question 7

which bases are purine?

Answer 7

adenine and guanine

Question 8

which bases are pyrimidine?

Answer 8

cytosine, thymine and uracil

Question 9

what bonds are found between nucleotides?

Answer 9

phosphodiester bonds

Question 10

how many hydrogen bonds are found between each of the bases?

Answer 10

2 for A=T and 3 for C≡G

Question 11

what are the ends of polynucleotides called?

Answer 11

three prime (3’) for the pentose end and five prime (5’) for the phosphate end

Question 12

what is the structure of chromosomes?

Answer 12

double helix polynucleotide chains wrapped around histone proteins, folded into condensed chromosomes

Question 13

how many chromosomes does a human diploid have?

Answer 13

46

Question 14

how many chromosomes does a human haploid have?

Answer 14

23

Question 15

what is a homologous pair?

Answer 15

a pair of chromosomes with the same genes (eg X and Y)

Question 16

what is a gene?

Answer 16

a section of DNA which codes for a specific polypeptide

Question 17

what is the difference between conservative and semi-conservative replication?

Answer 17

the entire original chromosome is retained vs half of it is used as a template strand

Question 18

which enzyme “unzips” polynucleotide chains?

Answer 18

DNA helicase

Question 19

how does DNA polymerase work?

Answer 19

it attaches to the 3’ end and moves in a 3’-5’ direction, forming phosphodiester bonds between the paired nucelotides

Question 20

what does DNA ligase do?

Answer 20

joins up the sections of the new 5’-3’ chain, since DNA helicase and DNA polymerase move in different directions on this chain

Question 21

what are the four main features of the genetic code?

Answer 21

it is universal, degenerate, non-overlapping and uni-directional

Question 22

what is the “start triplet”?

Answer 22

ATG - methionine

Question 23

what is pre-mRNA?

Answer 23

duplicated DNA before it has been spliced

Question 24

what enzyme joins mRNA nucleotides together?

Answer 24

RNA polymerase

Question 25

what is modification?

Answer 25

when a pre-mRNA strand is spliced using enzymes to remove introns (junk DNA) and the extrons reconnected

Question 26

what is the coding strand?

Answer 26

the DNA strand which is duplicated

Question 27

what is the template strand?

Answer 27

the DNA strand which RNA binds to

Question 28

what is mRNA?

Answer 28

the duplicated DNA strand

Question 29

what is the main structural difference between DNA and RNA?

Answer 29

DNA contains deoxyribose while RNA contains ribose

Question 30

what is the difference between triplets and codons?

Answer 30

triplets are found in DNA while codons are found in mRNA

Question 31

what is tRNA?

Answer 31

a molecule with a sequence of three bases called an anticodon, complementary to codons on the mRNA

Question 32

where does DNA transcription take place?

Answer 32

the nucleus

Question 33

where does DNA translation take place?

Answer 33

the cytoplasm (ribosomes)

Question 34

how is DNA transcription and translation different in prokaryotes?

Answer 34

takes place in the cytoplasm, chains can be longer, lifespan of prokaryotic mRNA is shorter (no introns), smaller ribosomes (multiple for each mRNA chain)