Unit 1: DNA & The Genome - Key Area 3: Gene Expression Flashcards
synthesis of different mature transcripts from the same primary transcript
alternative RNA splicing
unit of polypeptide structure
amino acid
sequence of three bases on tRNA that specifies an animo acid
anticodon
position on a tRNA molecule at which a specific amino acid binds
attachment site
sequence of three based on mRNA that specifies an animo acid
codon
includes: light, temperature, nutrients and other factors which can affect the phenotype of an organism
environmental factors
sequence of DNA that codes for part of a protein
exon
DNA sequence which codes for a protein
gene
transcription and translation of genetic information in a gene to produce a specific protein
gene expression
non-coding sequence of DNA within a gene
intron
carries a copy of the DNA code to a ribosome
mature mRNA
alternative term for mature mRNA
mature transcript
various chemical links joining amino acids and giving protein molecules their shape
molecular interactions
strong chemical links which join amino acids in the primary structure of polypeptides
peptide bonds
outward appearance of an organism
phenotype
short strand of amino acids
polypeptide
molecule made when DNA is transcribed
primary transcript
type of RNA that makes up ribosomes
rRNA
sugar component of an RNA nucleotide
ribose sugar
site of protein synthesis, composed of rRNA and protein
ribosome
ribonucleic acid, which occurs in several forms in cells
RNA
enzyme involved in synthesis of primary transcripts from DNA
RNA polymerase
joining of exons following the removal of introns from a primary transcript
RNA splicing
triplet transcribed from DNA to a fprimary transcript indicating the start of the gene
start codon
triplet on the primary transcript which signals a stop to translation
stop codon
copying of DNA sequence to make a primary transcription. Synthesis of mRNA from a section of DNA
Transcription
transfers specific amino acids to the mRNA on the ribosomes
tRNA
production of a polypeptide using sequences of mRNA
translation
RNA base not found in DNA but complementary to Adenine in translation
Uracil (U)
what are examples of protein controlling organisms
receptors, enzymes and hormones
function of mRNA
carries the genetic information to ribosomes in the cytoplasm
uses/ function of protein?
> produce pathogens
membrane: proteins are channels
structures: hair, nails, large % of skin
blood: haemoglobin protein carries oxygen in our blood
what are the three types of RNA?
> mRNA (messenger RNA)
tRNA (transfer RNA)
rRNA (ribosomal RNA)
differences between DNA and RNA?
> RNA is single stranded while DNA is double stranded
Instead of having Thymine as a base in RNA, it is replaced by Uracil
RNA contains ribose sugar not deoxyribose
how is mRNA formed?
transcribed from DNA in the nucleus (transcription)
function of mRNA
carries a copy of the DNA code from the nucleus to the ribosomes in the cytoplasm
why does tRNA fold?
due to complementary base pairing
function of amino acid
carries a specific amino acid to the ribosome
what are the 2 sites on a tRNA molecule which other molecules can attach?
> 3’ end attachment site
> anti codon (exposed triplet of bases)
what is the first step in the process of transcription/ producing mRNA?
RNA polymerase moves along DNA unwinding the double helix and breaking the hydrogen bonds between the bases (only happening at the gene end to be copied)
what is the second step in the process of transcription/ producing mRNA?
RNA polymerase adds RNA nucleotides onto the 3’ end of the growing mRNA molecule
what is the third step in the process of transcription/ producing mRNA?
the RNA polymerase synthesises a primary transcript of mRNA from RNA nucleotides by complementary base pairing, the base Adenine is paired with Uracil instead of Thymine.
what is the fourth step in the process of transcription?
The primary transcript of mRNA then undergoes splicing where non-coding introns are removed and the remaining exons are joint together forming a mature transcript of mRNA
what is the enzyme responsible for transcription
RNA polymerase
where does the process of transcription take place
in the nucleus
non-coding regions of mRNA
introns
coding regions of mRNA
exons
what does RNA splicing form?
mature mRNA transcript
what is splicing?
introns are removed from the primary transcript, exons are kept and joined together to form the mature mRNA transcript
what is alternative splicing?
different mature mRNA transcripts are produced from the same primary transcript depending on which exons are retained
what is the effect of alternative splicing?
different proteins can be expressed from one gene as a result of alternative RNA splicing
what is the first step of translation?
the mRNA molecule travels through the cytoplasm and attaches to the ribosome
what is the second step of translation?
tRNA transports specific amino acids to the ribosome
what is the third step of translation?
each mRNA codon codes for a specific amino acid so the first codon of an mRNA molecule is a start codon which signals the beginning of translation
what is the fourth step of translation?
A second tRNA molecule with the anti codon which has complementary base pairs to the second codon, binds to it.
what is the fifth step of translation?
A peptide bond then forms between adjacent amino acids to form a polypeptide (protein)
what is the sixth step of translation?
the first tRNA molecule leaves the ribosome and repeats the process to create a polypeptide chain
what is the seventh step of translation?
The last codon of an mRNA molecule is a stop codon, when this is reached it signals the end of translation
where does the modification of the primary transcript of mRNA occur
in the nucleus
where does the collection of amino acids by tRNA occur?
in the cytoplasm
where does the formation of codon-anti codon links occur
at the ribosome
what are the subunits of protein?
Carbon (C) Hydrogen (H) Oxygen (O) Nitrogen (N) Sulfur (S- only sometimes)
how many types of amino acids are there?
20
what is the length of protein molecules?
varies from few to many thousands
why does folding occur in the secondary structure of protein?
due to the hydrogen bonds between certain amino acids in a polypeptide chain
describe the protein primary structure
linked together by peptide bonds in a polypeptide chain
describe the protein secondary structure
due to hydrogen bonds, folding occurs between certain amino acids in a polypeptide chain
describe the protein tertiary structure
produced by additional bonds between amino acids in the chain e.g between sulphur atoms
describe the protein quaternary structure
the number and arrangement of multiple folded protein subunits are arranged together to form a 3D shape to carry out functions
why do proteins have a variety of shapes?
because their shape is determined by their functions
what influences phenotype?
environmental factors
what is phenotype determined by?
proteins produced as a result of gene expression
