Gene Expression (3) Flashcards
What is a genotype?
Is the combination of genes that a cell contains.
How is a cell’s genotype determined?
The sequences of bases in the genes determines the genotype of a cell.
What is a phenotype
A phenotype is the physical expression of the genes in a cell.
How is a cell’s phenotype determined?
It is determined by the proteins that are synthesised when the genes are expressed.
How much of the genes in a cell are expressed?
Only a fraction of the genes in a cell are expressed.
What affects gene expression?
The influence of environmental factors whether it be inside or outside (intra or extra-cellular).
What controls gene expression?
Gene expression is controlled by the regulation of the processes of transcription and translation.
What is a protein made up of?
One or more polypeptide chains.
What does RNA (Ribonucleic acid) do?
Provides a bridge between DNA and protein synthesis.
Where is RNA found?
Nucleus and Cytoplasm.
What are the three different forms of RNA?
rRNA
tRNA
mRNA
What does rRNA (ribosomal RNA) do?
It binds to proteins to form ribosomes which are the site of protein synthesis.
What does mRNA (messenger RNA) do?
It carries a copy of the DNA code from the nucleus to the ribosome.
What does tRNA (transfer RNA) do?
It pick up and carries a specific amino acid from the cytoplasm and carries it to the ribosome.
What is RNA in term of structure?
It is a single stranded molecule that is composed of nucleotides, which just like DNA contain a phosphate, a base and a sugar.
What is an RNA nucleotide made up of?
Base, ribose sugar and a phosphate.
What are the four bases that an RNA nucleotide can contain?
Adenine, uracil, cytosine and guanine
Meaning there are 4 different kinds of nucleotides.
What are the base pairing rules in RNA?
Adenine - Uracil
Guanine - Cytosine
What holds the bases together in an RNA nucleotide?
Weak hydrogen bonds.
What holds the nucleotides together in RNA?
Strong sugar (ribose) phosphate bonds.
What are amino acids?
They are the building blocks of proteins.
How many amino acids are there that exist naturally within cells?
20.
How many bases is DNA made up of?
4
How many amino acids could be coded for with the bases in DNA?
4 which would not be enough as when given a two letter code it would only result in 16 possible arrangements which is not enough as there are 20.
What is a triplet code?
A triplet code is a code consisting of 3 bases.
How many variations of amino acids can a triplet code produce?
64 which is more than enough as the required amount is 20.
How many bases/nucleotides code for an amino acid?
3.
What are the 2 main processes that take place during protein synthesis?
Transcription and Translation.
What is the first step in protein synthesis?
Transcription.
What does the process of transcription require?
DNA (to act as a template for the new RNA molecule)
RNA polymerase
A supply of four different nucleotides
ATP
