storing and using genetic information

Question 1

what is a phenotype?

Answer 1

outward physical manifestation of organism

Question 2

what is a genotype?

Answer 2

full genetic code of organism (even if not expressed)

entire DNA content

Question 3

what determines protein function?

Answer 3

protein structure

Question 4

what are the four different bases in DNA?

Answer 4

A
T
G
C

Question 5

what sugar is used in DNA monomers?

Answer 5

2-deoxyribose

Question 6

what is the difference between 2-deoxyribose and ribose sugars?

Answer 6

in ribose sugar there is an OH group on the 2’ carbon as opposed to an H in 2-deoxyribose

Question 7

what direction do the polynucleotide chains run in in relation to each other?

Answer 7

anti parallel

Question 8

what bases bind to each other?

Answer 8

A - T (or uracil in RNA)

C-G

Question 9

where does replication of DNA and the first steps in decoding it for protein production take place?

Answer 9

nucleus

Question 10

what is the DNA molecule packaged into in the nucleus?

Answer 10

chromosomes

Question 11

what is a chromosome?

Answer 11

single piece of DNA containing many genes, regulatory elements and other nucleotide sequences

Question 12

what is DNA wrapped around in order to shorter its length?

Answer 12

histones

Question 13

what is chromatin?

Answer 13

mixture of DNA, proteins and RNA that package DNA within the nucleus

Question 14

what are the two forms of chromatin?

Answer 14

heterochromatin (inactive)

euchromatin (active)

Question 15

why does banding occur in chromosome?

Answer 15

due to different densities of packaged DNA

Question 16

why does the cell have to copy its DNA completely in order to divide?

Answer 16

so that both daughter cells have a full set of chromosomes

Question 17

why does the DNA helix have to separate before it can be replicated?

Answer 17

to allow enzymes access to the DNA template

Question 18

what are the two major mechanisms by which chromatin is made more accessible?

Answer 18

histones can be enzymatically modified

histones can be displaced by chromatin remodeling complexes

Question 19

what is semi conservative copying?

Answer 19

one half of each new DNA molecule is new and one is old

Question 20

what is bi-directional replication?

Answer 20

replication in 2 directions

Question 21

what direction is DNA replicated in?

Answer 21

5’ end to 3’ end

Question 22

how much of the human genome codes for proteins?

Answer 22

less than 2%

Question 23

what are introns?

Answer 23

non coding regions

Question 24

what are exons?

Answer 24

coding regions

Question 25

what is a codon?

Answer 25

set of 3 bases

Question 26

what does each codon specify?

Answer 26

a particular amino acid

Question 27

how many codons are there?

Answer 27

64

Question 28

how many amino acids are found in proteins?

Answer 28

20

Question 29

whar is the initiation codon?

Answer 29

methionine

Question 30

what mutation occurs in sickle cell anaemia?

Answer 30

glutamate is substituted for valine, (GAA or GAG becomes GUA or GUG)

Question 31

what is the role of RNA?

Answer 31

participate in protein synthesis

Question 32

what does mRNA carry?

Answer 32

information for protein synthesis

Question 33

what is alternative splicing?

Answer 33

process by which the exons of RNA produced by transcription of a gene are reconnected in multiple ways - means one gene can code for multiple proteins

Question 34

what is the purpose of a stop codon?

Answer 34

prevents the wrong protein being synthesised

Question 35

what is the open reading frame?

Answer 35

set of codons that run continuously and are bounded by a start/initiation codon and a termination codon

Question 36

what is the role of tRNA?

Answer 36

translate mRNA sequence into amino acid sequence - brings proteins to ribosomes

Question 37

what does rRNA do?

Answer 37

combines with proteins to form a ribosome

Question 38

what is a polysome?

Answer 38

several ribosomes translating mRNA at one time.