6.1.1 Flashcards
What is a gene?
section of DNA that codes for a polypeptide
What is a polypeptide?
chain of amino acids joined by peptide bonds
What is a genome?
all the genetic material in an organism, including genes and non-coding DNA
What is a protein?
1or more folded polypeptide chains
What is a histone?
protein DNA wraps around to form chromatin. Allows DNA to be more compactly packaged
What is transcription?
Process of copying DNA base sequence to produce a specific polypeptide chain
What is a mutation?
change to the DNA bases / nucleotides
What are gene mutations?
changes to the base sequences of genes in DNA
What is a substitution gene mutation?
One or more bases are swapped for others
What are the 3 types of substitution gene mutation?
Mis-sense
Non-sense
Silent
What is insertion?
One or more bases are added into the sequence of the gene
What is deletion?
One or more bases are removed from the sequence of a gene
What does insertion and deletion cause?
a frameshift
What is a mis-sense mutation?
when substitution causes a different amino acid to be coded for
What will happen to the protein as a result of the mis-sense mutation?
- primary structure changes
- may change tertiary structure
- changes overall 3D shape of protein
- functionality of protein likely to change
What is a non-sense mutation?
a substitution changes a codon that codes for an amino acid into a stop codon
What happens to the protein as a result of the non-sense mutation?
- produced a shorter polypeptide chain
- that is likely to fold differently
- functionality of protein is likely to change
What is a silent mutation?
where a substitution occurs that has no effect on the amino acid coded for due to the degenerate nature of the code
What happens in a frameshift?
- reading frame will now line up different incorrect triplets after the point of mutation
- significant effect on function of protein
End of cellular control A
Start of cellular control b
What does the regulatory gene product do?
switches on/off gene
What does the structural gene product do?
makes enzymes like beta galactosidase
How does RNA polymerase bind to the promoter?
when lactose is present, it binds to the repressor protein
repressor protein changes shape
stops the repressor protein binding to the operator
RNA polymerase can now bind to the promoter
Structural enzymes can now be transcribed
What does RNA polymerase bind to when lactose is present?
repressor protein
What happens to the repressor protein when RNA polymerase binds to it?
changes shape and cannot bind to the operator
What happens now that the repressor protein has changed shape?
RNA polymerase can now bind to the promoter
Structural enzymes can now be transcribed
What are introns?
non-coding regions inside genes
What are exons?
coding regions in genes
Where os non-coding DNA found?
within genes and between genes
What is splicing?
removing introns to produce mature mRNA
mRNA modified
What happens when splicing changes?
different versions of mRNA can be produced
What does cAMP do?
activates proteins insider the cell by altering 3D structure
activates protein kinases
What do protein kinases do?
they activate other proteins by phosphorylation
End of B
Start of C
What is a homebox sequence?
a group of regulatory genes
covers a section of DNA for 180 base pairs = 60 Amino acids
What is the homeodomain?
proteins made from the homeobox
What do homeodomain proteins do?
proteins bind to DNA and switch genes on/off
control the body plan
What are hox genes?
a group of homeobox genes in animals that are responsible for the position of body parts
duplicated over time
What does the order/sequence of these genes determine?
head-tail oreintation
segments
position of limbs
position of eyes
Why is it ideal to use a fruit fly for studies into the homeobox?
small
short life-cycle
easy to keep/breed
cheap to buy / not rare
large cells
previously well-studied / many known mutants
What can affect homeobox development?
internal factors
external factorsq
What internal factors effect the homeobox development?
hormones
What external factors affect homeobox development?
temperature
drugs
What is apoptosis triggered by?
transcription factors made by Hox genes breaking down cytoskeleton
What does transcription factors made by the hox genes cause?
cytoskeleton to be broken down by lysosomes
How do the transcription factors break down the cytoskeleton?
lysosomes / enzymes
How are blebs formed?
changes in the cell surface membrane
How does the cell break off in segments in apoptosis?
cell breaks off in segments
What happens to the segments in apoptosis?
segments are digested
phagocyotiss
What is an operon?
A cluster of genes under the control of a promoter
