DNA - sec1 Flashcards
What does DNA stand for?
DeoxyriboNucleic Acid
What is the DNA’s function?
It is a chemical that all the genetic material in a cell is made up from
What does DNA contain?
Coded information - Instructions to put an organism together and make it work
What determines your inherited characteristics?
What’s in your DNA
Name where DNA is found.
Nucleus of animal and plant cells, in really long structures - chromosomes
Name the features of a chromosome.
Long, thread-like structures
What do chromosomes come in?
Normally in pairs
Name a polymer.
DNA
What is a DNA made up of?
Two strands coiled together - shape of a double helix
What does a gene code for?
A specific protein
Define a gene.
A small section of DNA found in a chromosome
What does EACH gene code for?
A particular sequence of amino acids which are put together to make a specific protein.
What do genes tell cells?
In what order to put amino acids together
What does DNA determine?
What proteins the cell produces - Haemoglobin/Keratin
Which determines what type of cell it is - Red blood cell /Skin cell
Define a genome.
Entire set of genetic material in an organism
True or False - Scientists have worked out the complete human genome.
True
Why is understanding the human genome a really important tool?
For science and medicine:
- Identify genes that link to different types of diseases
- Knowing genes linked to inherited diseases will help understand them better and develop effective treatments
- Trace migration
How do scientist trace migration in a human genome?
All modern humans descend from a common ancestor who lived in Africa, now humans are all over the world - the human genome is identical in all individuals.
But as people migrated away from Africa, gradually develop tiny differences in genomes.
Investigating these differences, scientists can work out when new populations split off in a different direction and what route they took.
Define a nucleotide.
Repeating units
Name a polymer.
DNA strands
What does each nucleotide consist of?
One sugar molecule, one phosphate molecule and one ‘base’
What does the sugar and phosphate molecule produce?
In the nucleotide it forms a ‘phosphate backbone’ to the DNA strands
What are sugar and phosphate molecules?
Alternate
What does each base link to?
A base on the opposite strand of the helix
Give examples of complimentary base pairing?
A always pairs up with T
C always pairs up with C
What does the order of bases in a gene decide?
The order of amino acids in a protein
What does each amino code for?
A sequence of three bases in the gene
What does the amino acids join together to make various proteins?
Depending on the order of the genes bases
True or False : Are there parts of DNA that don’t code for proteins.
True
What do DNA do when their parts don’t code for proteins?
Some of these non-coding parts switch genes on and off, so they control whether or not a gene is expressed
(used to make a protein)
What does mRNA carry?
The code to the ribosomes
Where are proteins made?
Cell cytoplasm on ribosomes
What features do ribosomes have?
Tiny structures
How do you make proteins?
Ribosomes use the code in the DNA. DNA is found in the cell nucleus and can’t move out = big.
So the cell needs to get the code from the DNA to the ribosomes
What is used to make proteins?
mRNA
What does mRNA do?
Copying the code from DNA
What does the mRNA act as?
Messenger between the DNA and the ribosome - it carries the code between the two
What is brought to the ribosomes in the correct order by carrier molecules?
The correct amino acid
Name protein functions
Enzymes
Hormones
Structural proteins
What do enzymes do?
Act as biological catalyst to speed up chemical reactions in the body
What do hormones do?
Carry messages around the body.
Insulin is a hormone released into the blood by pancreas to regulate the blood sugar level
What do structural hormones do?
Physically strong
Collagen is a structural protein that strengthens connective tissues - ligaments/cartilage
Define mutations.
Are random changes to the genetic code.
State what might a gene occasionally do?
Mutate
State what genes can sometimes be?
Inherited
What do mutations occur?
Continuosly
Explain what mutations also occur?
Spontaneously - When a chromosome isn’t quite replicated properly.
However, the chance of mutation is increased by exposure of certain substances or some types of radiation
What do mutations change?
The sequence of DNA bases in a gene which produces a genetic variant
Define genetic variant
A different form of the gene.
How do mutations lead to changes to proteins?
As the sequence of DNA bases code for the sequence of amino acids that make up a protein, mutations to a gene sometimes lead to changes in the protein that it codes for.
What do most mutations have on proteins?
Very little or no effect - some proteins will change it such a small extent that its function/appearance is unaffected
What do some mutations have on proteins?
Seriously affect - sometimes the mutation will code for an altered protein with a change in it’s shape.
How does the mutation affect on an altered protein with a change in its shape?
It could affects its ability to perform its function
What happens if the shape of an enymes active site is changed?
It’s substrate may no longer be able to bind it
What happens if the structural proteins - collagen lose their strength if their shape is changed?
Making them pretty useless at providing structure and support
What occurs if there’s a mutation in non-coding DNA?
It can alter how genes are expressed
What are insertions?
Where a new base is inserted into the DNA base sequence where it shouldn’t be
What does an insertion change?
The way the groups of three bases are ‘read’ which can change the amino acids that they code for
What can insertions change?
More than one amino acids as they have a knock-on effect on the bases further on in the sequence
What are deletions?
Deletions are when a random base is deleted from the DNA base sequence
What can deletions change?
They can change the way that the base sequence is ‘read’ and have a knock-on effect further down the sequence.
What are substitutions?
Substitution mutations are when a random base in the DNA base sequence is changed to a different base
