B1.2 - What happens in cells? Flashcards
What does DNA stand for?
DNA is deoxyribose nucleic acid
What is DNA ?
It is the genetic material found within the nucleus of every one of your cells.
State the role of DNA in the body ?
DNA is the substance that contains all the instructions that determine your characteristics
What units/ monomers make up the polymer DNA?
Nucletoides
What is a nucleotide composed of ?
1 phosphate, 1 deoxyribose sugar + 1 organic base
What are the 4 organic bases called ?
Thymine, Adenine, Guanine + Cytosine
What is a gene ?
A short section of DNA found upon a chromosome which codes for a specific protein
What it complementary base pairing?
Adenine - Thymine
Cytosine - Guanine
What is the name of the structure formed by DNA, as discovered by Watson and Crick in the 1950s ?
Double Helix
Who produced the first ever photograph of DNA, ‘photo 51’, that led to the discover of DNA’s structure ?
Rosalind Franklin
Why is the double helix described as being ‘anti-parallel’?
The two strands which form DNA are parallel but run in opposite directions
Where are the phosphate and deoxyribose molecules in a DNA polymer joined from ?
The sugar-phosphate backbone
What is the name of the weak bonds formed between bases of opposing strands of DNA?
Hydrogen bonds
What is each long molecule. of DNA called ?
Chromosome
Place in size order: gene, chromosome, genome, DNA, nucleus, cell, nucleotide
Nucleotide (smallest)
Gene
DNA
Chromosome
Genome
Nucleus
Cell (largest)
Name the tow stages of protein synthesis ?
Transcription Translation
Where does protein synthesis take place
A
Transcription - starts in the nucleus, and ends when the mRNA strand leaves through the nuclear pore to towards the ribosomes Translation - In the cytoplasm with the assistance of ribosomes
Define transcription
The process by which DNA unzips to allow mRNA to use it as a template to make a copy of a section which codes for a specific protein. Once copied the mRNA detaches and leaves the nucleus and the DNA zips back up.
Define translation.
The process by which mRNA is read by the nucleus in groups of three ‘codons’, to produce a protein. During translation tRNA molecules are attracted to their complementary bases upon the mRNA bringing specific amino acids with them that join together into a chain to form a protein.
What are the key differences between DNA and RNA?
DNA
Deoxyribonucleotides
Bases: A, T, C, G
Sugar: deoxyribose
Double helix
Can not leave the nucleus
Long polynucleotide chain
DNA is completely protected by the body from degradation.
Self-replicating
RNA
RNA
Ribonucleotides
Bases: A, U, C, G
Sugar: ribose
Single strand
RNA can move in and out of the nucleus.
Short polynucleotide chain
Strands are continually made, broken down and reused
Synthesized from DNA on an as-needed basis.
What are enzymes?
Proteins which act as biological catalysts - meaning they speed up reactions without being used up in the process.
What is the name of the molecule that an enzyme binds to?
Substrate
What is an ‘active site’?
An active site is part of an enzyme that binds to the substrate. It has a specific shape which is formed by the way its amino acids are folded togther within the protein.
This hypothesis states that only one substrate will fit one enzyme, and that they must be an exact fit.
Lock and key hypothesis
Q
What is formed when a substrate binds to an enzyme
Enzyme-substrate complex
State the factors affecting enzyme activity?
Temperature
pH
Substrate availability/concentration
Enzyme concentration
What is the affect of temperature upon enzyme activity
The rate of reaction increases as increase kintetic energy, means increased number of successful collisions.
The higher the temperature, the faster the reaction
If the temperature becomes too high the enzyme denatures
What does ‘denatured’ mean?
The structure of the protein that forms the enzyme has been altered due to high heat or a change in pH.
The change in shape affects the active site
The substrate can no longer bind with the enzyme
If an enzyme is denatured, what happens to the rate of reaction?
As the enzyme can no longer catalyse the reaction, the rate of reaction decreases.
How does substrate concentration affect enzyme-controlled reactions?
The higher the substrate availability the higher the rate of reaction until all the enzyme-substrate bases are used up.
