DNA and Proteins Flashcards
(41 cards)
what is the process of DNA replication
An enzyme, DNA helicase unzips DNA’s double helix by breaking the hydrogen bonds between the nucleotides, then free nucleotides bond to their complementary base of the unzipped strands. DNA ligase then joins the sugar-phosphate backbone of nucleotides creating a new backbone. Two identical sets of DNA are then produced
What is DNA’s structure
DNA is constructed of 2 complementary strands that are twisted into a double helix structure. The backbone of DNA’s double helix is made up of alternating deoxyribose sugar and phosphate groups. In DNA there are 4 nucleotide bases used throughout the strands that are connected by hydrogen bonds. They thymine, adenine, guanine, and cytosine.
Explain why DNA methylation can alter gene expression
when a cytosine gets methylated it causes the RNA polymerase to have difficulty accessing the gene, therefore the expression of a particular gene is reduced
What are enzyme-controlled reactions affected by
Temperature - each enzyme has an optimum temperature at which its reaction rate is greatest. Rate of enzyme-controlled reactions increases with temperature as substrates move more rapidly colliding with active site more. However, above optimum temperature the enzyme can denature as thermal agitation of the enzyme molecule distrupts the weak interactions that stabelise enzyme structure and active site.
pH -
Substrate concentration
Enzyme concentration
What are competetive inhibitors
they compete with substrates for an enzymes active site
What are non-competetive inhibitors
The alter an enzymes active site shape by binding to the enzyme away from active site
What are mutations
changes in dna sequence
process of translation
the mRNA strand leaves the nucleus via pores and enters the cytoplasm to find a ribosome. In the ribosome tRNA molecules with an anticodon on the end and amino acid on top line with their complementary codon on the mRNA strand then as other tRNA molecules find their complementary condon the previous tRNA molecule is ‘bumped off’ and their amino acid is deposited and attached to the next tRNA’s amino acid. This continues until a stop codon is reached and a polypeptide chain is produced
What is transcription
this is the process where a complementary section of a gene on a mRNA is produced that can be taken out of the nucleus to be translated into a protein
what does the induced fit model do
the induced fit model brings chemical groups to the active site into position to catalyse chemical reactions
What is semi-conservative replication
Describes that when each DNA replicated has an old half and a new half of nucleotides and backbone, as one strand comes from the original DNA molecule and one strand is produced from polymerase and ligase
Describe CRISPR to edit and transfer genes
1 - the Cas 9 protein forms a complex with a guide RNA in a cell
2 - this complex then attaches to part of a target gene
3- the active sites of Cas 9 then cuts the DNA on both strands
4 - then the broken parts of the cells are repared by scientists disabling target gene. Then repair enzymes insert or delte nucleotides so it no longer functions. If the target gene however was mutated a new copy of the correct nucleotide sequence is instered to synthesise and correct gene.
How do Enzymes increase reaction rate
they lower the activation energy barrier which allows the molecules to absorb enough energy to reach the transition state lower temperatures
What is the organisational flow of protein synthesis
DNA - (transcription) - RNA - (translation) - protein
What are the coding and template strands of DNA
DNA is made up of 2 strands: template and coding.
Template - strand that is transcribed to produce mRNA molecule
Coding - strand that is no turned into mRNA molecule
Describe a method how select genes are transferred - Microinjection
how are genes removed
if a sequence of what is looked for is known a restriction ezyme can be used to cut the specific gene out of the DNA.
difference in mutations in germ and stomatic cells
stomatic cells are regular body cells involved in reproduction of the organism. If mutations occur in stomatic cells it is limited to the desendents of that specific cell with the mutation - if foes not effect the offspring
Germ cells are the sex cells of the organism (sperm/ova) therefore if mutated and there is fertilisation from that the offspring will produce such mutation in every cell in their body
How do the bonds between nucleotides allow replication
hydrogen bonds are strong in terms of secondary interactions, however they can be easily broken through the process of bond dissociation. Therefore, a DNA strand can be easily broken to separate from its complementary strand throug the input of erngy from the enzyme or heat
Dna in prokaryotes
prokaryotes have a single circular chromosome that floats freely in the cytos. The prokaryotes chromosome does not have any proteins attached
what are the DNA base parings
Adenine bonds with thymine
Guanine bonds with cytosine
why is 3D shape of protein crucial to its function
A proteins function is determined by its sequence of amino acids due to it detrming 3D shape. Thus a specific order of amino acids is specific to one protein. The order of subunits is crucial to the function of proteins as if a change in amino acid sequnces occurs its function will be altered and how it interacts due to the change in shape.
eg. enzyme activesite no longer complementary to substrate
what is translation and what happens
translation is when the mRNA enters the ribsome to be translated into a polypetide. In the ribosome the mRNA codons read and translate to a specific amino acid with tRNA bringing the needed amino acid
how/why is mRNA modified
the mRna produced from genes includes introns and exons in their primary sequence, thus before an mRNA is coded for a protein the introns are removed and the exons are spliced together to make mature RNA
