Gene expression Flashcards
What does every cell in a multicellular organism contain?
A complete set of chromosomes with every gene needed to make every protein the body will ever make
How many genes in the chromosomes will be expressed?
A very small fraction in any particular cell
What is each cell?
Specialised to perform a certain task, only needing to express certain genes
What is gene expression?
Gene expression is the process by which specific genes are activated to produce a required protein
What is a phenotype?
An organisms phenotype is determined based on protein produced, depending on environmental factors
What is the gene expression process made up of and what does it involve?
The gene expression is made up of translation and transcription processes, it involves RNA
What is RNA?
RNA is a type of nucleic acid called ribonucleic acid
What do RNA nucleotides come together to form?
RNA nucleotides come together to form a single strand
How are RNA nucleotides held together?
With strong covalent bonds between the sugar of one nucleotide to the phosphate of another
In what ways to DNA and RNA differ?
RNA is single stranded whilst DNA is double stranded
RNA has a sugar called ribose whilst DNA has a sugar called deoxyribose
RNA has the base uracil while DNA has base thymine
How many types of RNA are involved and gene expression and what are they?
mRNA, tRNA, rRNA
What is mRNA?
Messenger RNA (mRNA) is a linear molecule that carries a copy of the gene to be expressed from the nucleus to the ribosomes in the cytoplasm.
What is tRNA?
Transfer RNA (tRNA) has a cloverleaf shape. It is made from a single strand of RNA which folds due to base pairing, forming its odd shape. It has a triplet anti codon site and an attachment site for a specific amino acid. It carries specific amino acids to ribosomes where they can be assembled to form polypeptide chains
What is rRNA?
Ribosomal RNA (rRNA) and proteins form the ribosome. The ribosome is the structure where protein synthesis takes place
What is a gene?
Genes are DNA sequences that code for a protein
What is an unusual feature of most genes?
That the sequence of nucleotides that code for a protein is regularly interrupted by none coding stretches of DNA
What are the coding regions of a gene called?
Exons
What are the non coding regions of a gene called?
Introns
What is RNA splicing?
When genes are to be expressed by a cell, the non coding sequences of DNA must be edited out before they can be turned into a protein
What is a protein molecule?
Polypeptide chain
What is a poly peptide chain?
A sequence of amino acids held together by peptide bonds
How proteins vary in shape? what is the importance of this?
A polypeptide chain is folded into a three-dimensional shape held in place by hydrogen bonds and other interactions between induvial amino acids. The shape of a protein is linked to its function
What are the stages of gene expression?
Two main stages, transcription and translation
What happens in transcription?
A copy of the gene in the form of mRNA is created
