The Genetic Code Flashcards
What is a gene and its function?
Genes are made up of DNA. Some genes act as instructions to make molecules called proteins. With introns for sections of non-coding DNA and exons as sections of coding DNA.
What is a protein and its function?
This is a long chain of amino acids - essential for cell structure and functioning - building muscle (structural), enzymes, regulate metabolic processes (enzymes), etc. This enabled processes such as transport across the membrane (channels), communication (hormones).
What is an enzyme and its function?
The most important protein is able to speed the rate of chemical reactions (catalyse them) - with the purpose of maintaining cell function/growth.
Outline the stages of Protein Synthesis (Transcription).
The process by which a genes DNA sequence is copied into mRNA.
1) DNA molecule is unzipped by an enzyme at a particular location - exposing nitrogenous base code.
2) One exposed strand is a template for mRNA construction.
3) RNA polymerase moves along this strand and adds new nucleotides to make mRNA (A-U, C-G, etc.).
DNA - mRNA:
AAG - CCG - TTT - AGA - GAG - ATT
UUC - GGC - AAA - UCU - CUC - UAA
A new piece of mRNA leaves the nucleus to the cytoplasm, carrying genetic message to the ribosomes; protein synthesising construction.
Outline the stages of Protein Synthesis (Translation).
The process in which the genetic code carried by mRNA directs ribosomes to connect AA together; making proteins.
1) A ribosome attaches to one end of mRNA at a certain sequence of bases; binding site.
2) The ribosome moves along the mRNA three bases (codon) at a time reading the code of bases.
3) Once the ribosomes reach the AUG (start codon) of the mRNA - A tRNA with the corresponding anti-codon with attached AA joins matching base pairs.
4) The chain is progressed with matching anti-codons from the tRNA forming an AA chain until the ribosomes reach a stop codon.
5) The AA chain is in a corresponding sequence of base codons of original DNA - Forming a polypeptide bond between adjacent AA’s.
6) Once joined up they peel away from the tRNA molecules. mRNA is broken down by the cell to make nucleotides available for further use in other transcription.
What is the genetic code?
Sequence of AA is defined by a gene. Base sequence - instructions for protein construction.
The set of rules used by living cells to translate information encoded within genetic material into proteins.
What is gene expression?
Conversion of the genetic code carried by DNA into an end product (protein) - involves transcription/translation.
Outline how environmental influences can impact phenotypic gene expression.
Certain environmental influences can favour certain traits of an organism - increasing variety of a population - sheep grow thicker wool in winter to keep warm.
What are the key differences in RNA and DNA?
RNA - contains the sugar ribose, single-stranded, contains uracil and rest (no thymine), shorter than DNA (<4000 nucleotides).
DNA - contains the sugar deoxyribose, double-stranded, contains all nucleotides (no uracil), much loner than RNA.
Outline the splicing method.
- When mRNA strand has been synthesised from the DNA template strand - introns removed from mRNA.
- A methyl group (cap) is added to the 5’ end of mRNA.
- A number of adenine nucleotides are added to the 3’ end of mRNA.
- Stabilising the strand for translation.
Outline the folding process.
Determines Protein structure - formation of an amino acid chain from non-covalent bonds - slight change of shape can make the protein non-functional.
Types: Primary, secondary, tertiary, quaternary.
What is Epigenetics?
Epigenome - chemical factors controlling gene expression.
Epigenetic - changes in gene expression that can’t involve changes in a cell’s DNA but can be hereditary.
Variation in characteristics may be the result of gene expression, environmental effect, etc.
