key area 1.3 - gene expression Flashcards
1
Q
amino acid
A
- the basic building blocks of protein/unit of polypeptide structure
2
Q
4 types of proteins
A
- hormones : acts as a chemical messenger
- enzymes : biological catalysts that possess an active site that binds with specific substrate
- antibodies : made by blood white cells to defend body against pathogens
- structural
3
Q
chromatography
A
- technique used to separate components of a mixture which differ in their degree of solubility in solvent
4
Q
gel electrophoresis
A
- technique used to separate electrically caged molecules by subjecting them to an electric current which forces them to move through a sheet of gel
5
Q
peptide bond
A
strong chemical link that joins amino acids in a polypeptide chain
6
Q
polypeptide
A
chain like molecule composed of several amino acids
7
Q
protein
A
- molecule composed of one or more polypeptides folded or coiled into a specific shape
8
Q
anticodon
A
- triplet if bases on a tRNA molecule which is complementary to an mRNA codon
- specifies an amino acid
9
Q
tRNA attachment site
A
- region of a tRNA molecule to which a specific amino acid becomes temporarily fixed
10
Q
codon
A
- unit of genetic information consisting of three mRNA bases
11
Q
exon
A
- sequence of DNA that codes for part of a protein/coding region
12
Q
intron
A
non coding sequence of DNA within a gene
13
Q
differences between RNA and DNA
A
- DNA is double stranded, RNA is single stranded
- bases on DNA are ATGC and on RNA AUGC
- DNA has deoxyribose sugar and RNA has ribose sugar
14
Q
mRNA (messenger)
A
- carries copy of DNA code to ribosome
15
Q
tRNA (transfer)
A
- type of nucleic acid which carries a specific amino acid to a ribosome
16
Q
rRNA (ribosomal)
A
- type of RNA that makes up a ribosome
17
Q
primary transcript
A
- mRNA starts formed as the compliment of a DNA strand
- made when DNA is transcribed
18
Q
ribosome
A
- sub cellular structure made of rRNA and protein
- site of protein synthesis
19
Q
RNA polymerase
A
- enzyme which controls transcription
- it unwinds and unzips the DNA, breaking hydrogen bonds and exposing bases
20
Q
RNA splicing
A
- this is when exons are joined from a primary transcript of RNA (after introns are removed) to form the mature transcript
21
Q
what is transcription
A
- process by which a complementary molecule of mRNA is made from a region of a DNA template
22
Q
what is translation
A
- production of a polypeptide using sequences of mRNA
23
Q
uracil
A
- base present in RNA which is complementary to adenine
- replaces thymine
24
Q
alternative RNA splicing
A
- alternative splicing is when sections of the primary transcript can be treated as both introns and exons
- different exons are spliced together to form the mature transcript
25
Q
start and stop codons
A
- start codons cause RNA polymerase to start transcription/ cause a ribosome to start synthesising a polypeptide chain
- stop codons cause transcription to stop/ bring polypeptide chain synthesis to stop
26
Q
what binds holds polypeptides into a coil
A
- hydrogen bonds
27
Q
process of transcription
A
- RNA polymerase moves along section of DNA unwinding it and exposing no the bases
- molecule unzips when hydrogen bonds are broken
- mRNA nucleotides align with complementary base pairs on the template strand at the 3’ end
- strong chemical bonds form between adjacent nucleotides, building mRNA strand
- temporary hydrogen bonds between mRNA and DNA strand are broken allowing the primary transcript to separate from the template strand
- primary transcript undergoes RNA splicing to form the mature transcript which goes to the ribosome for translation (introns removed)
- DNA molecule reforms
28
Q
process of translation
A
- tRNA molecules attach to an amino acid in the cytoplasm and carry it to the ribosome (each tRNA specific amino acid)
- the first tRNA molecule moves in by means of base pairing between the anticodon on the tRNA and complementary codon in the mRNA strand
- this process is repeated with another amino acid and they line up beside each other and a peptide bond forms between amino acids
- the first tRNA detaches from mRNA strand and is free to collect another amino acid
- translation proceeds as ribosome moves along mRNA and as it continues it forms a polypeptide chain
