6.1 Flashcards
what is a mutation
a random change in the genetic material of an organism
what are the two main classes of DNA mutation
- point mutation, one base pair is substituted for another
- insertion or deletion, one or more nucleotides are inserted or deleted from a length of a DNA
what are the three types of points mutations
- silent
- missense
- nonsense
what is a silent mutation
a point mutation involving a change to the base triplet, where the triplet still codes for the same amino acid
what is a missense mutation
a point mutation where a change in the base triplet that leads to a change in the amino acid sequence in a protein
what is a nonsense mutation
a point mutation that may alter a base triplet so it becomes a stop codon
what are indel mutation
insertion and deletion mutations the can cause frameshift
what is a frameshift
when the dna is read incorrectly due to an insertion or deletion
what are expanding triple nucleotide repeats and how do they increase
some genes contain a repeating triplet such as CAG CAG CAG, the number of CAG triplets increases at meiosis and again from generation to generation
what are 2 examples of neutral mutations in humans
- inability to smell certain flowers like honeysuckle
- different shaped ear lobes
what are exons
the coding regions of DNA
what are introns
the non-coding regions of DNA
what does the bacterium E.coli normally metabolise
glucose
if lactose is present (glucose is absent) what 2 enzymes did lactose induce the production of
- lactose permease
- beta galactoside
what does lactose permease do
allows lactose to enter bacteria cell
what does beta galactoside do
hydrolyses lactose to glucose and galactose
What does the lac operon contain
Regulatory gene Promoter region Lac O Lac Z Lac Y
What does the regulatory gene do when there is glucose present
Codes for a repressive protein that binds to the operator region preventing RNA polymerase from binding to the promoter region so lac Z and Lac Y are not expressed
What does the regulatory gene do when there is lactose instead of glucose present
Regulatory gene produces a repressor protein and the lactose molecules binds to the repressor protein which changes its shape so it can’t bind to the operator region so RNA polymerase can bind to the promoter region which means lac Z and lac Y can be expressed
What are transcription factors
Are proteins, or non coding pieces of RNA, that act within the cells nucleus to control which genes in a cell are turned on or off
What do transcription factors do
They slide along a part of the DNA molecule, seeking and binding to their specific promoter regions and activate or suppress transcription of a gene
What are introns
Non coding regions of DNA
What are exons
Coding regions of DNA
What needs to be done to mRNA before it is ready for translation and why
When DNA is turned into mRNA the resulting mRNA is called primary mRNA, however this is too big to leave the nucleus so the primary mRNA is spliced to remove introns and joining exons to make secondary mRNA which is small enough to leave nucleus
How are proteins activated after translation
They are phosphorylated
What is apoptosis
Programmed cell death
