Module 6 Flashcards
(38 cards)
How can the sequence of bases in DNA change (a mutation)?
Substitution, deletion or insertion of one or more nucleotides within a gene
How can chromosome mutations occur?
Deletion, duplication, translocation or inversion
Hoe can genes be regulated by the level of which they operate?
Transcriptional-genes can be turned off or on
Post-transcriptional=mRNA can be modified which regulates translation and the types of proteins produces
Translational=translation can be stopped or started
Post-translational=proteins can be modified after synthesis which changes their function
Describe chromatin remodelling
Type of transcriptional control
-Hetrochromatin is tightly wound DNA, euchromatin is loosely wound
-Transcription can’t occur when tightly would because DNA polymerase can not access the genes
Histone modification
Describe histone modifiction
Type of transcriptional control
- Acetylation reduced positive charge on histones, DNA coils less tightly so transcription can occur
- Methylation makes histones more hydrophobic so they are kind tightly to each other, preventing transcription
Describe the lac operon
Type of transcriptional control
- When lactose is present, it binds to the repressor causing it to change shape so that it can no longer bind to the promotor.
- Transcription can then occur
What is the role of cAMP in the lac operon
cAMP binds to the repressor protein and speeds up trnscription
Describe RNA processing
Type of post-transcriptional control
- A cap is added to the 5’ end and a tail is added to the 3’ end
- This stabilises the mRNA and delays degradation in the cytoplasm
- The cap also aids binding of mRNA to ribosomes
- Splicing occurs, the irons are removed and the externs join together
Describe RNA editing
Type of post-transcriptional control
-The nucleotide sequence of mRNA can be changed through addition, deletion of substitution to synthesis different proteins
Describe translational control
- Degredation of mRNA
- Binding of inhibitory proteins to mRNA prevents binding to ribosomes
- Proteins kinases catalase the addition of phosphate groups, changing the tertiary structure and function of a protein
Describe post-translational control
- Addition of non-protein groups
- Modifying amino acids and the formation of bonds
- Folding or shortening of proteins
What is the homebox?
A section of DNA Highly conserved (similar) in plants, animals and fungi Homeobox genes are regulatory genes as they can be switched on or off
What are hot genes responsible for?
Correct positioning of body parts
What is apoptosis?
Programmed cell death, essential for shaping organisms.
What is chlorosis?
When leaves look pale or yellow due to a lack of chlorophyll being produced
Its as a result of environmental factors (lack of light, minerals, virus infections)
Dihybrid cross F2 generation ratio is…
9:3:3:1
What are recombinant offspring?
Offspring have different combinations of alleles than either parent
What is epistasis?
The interaction of genes at different loci
An epistatic gene may influence the activity of other genes
What is stabilising selection?
The average is selected for and the extremes are selected against
What is directional selection?
Occurs when theres a change in the environment and the most common phenotype is no longer advantageous.
Allele frequency shifts towards extreme phenotypes and evolution occurs
What is disruptive selection?
The extremes are selected for and the norm is selected against
What is allopatric speciation?
More common speciation.
Some members of a population are separated by a physical barrier and are geographically isolated
What is sympatric speciation?
Occurs within populations that share the sma habitat.
More common in plants than animals
When 2 different species interbreed and form a hybrid which can not interbreed. This reproductively isolated the hybrid organisms
How is a DNA profile produced?
DNA is extracted
-Polymerase chain reaction gives enough DNA to develop a profile
Sample is digested
-Restriction endonuclease cut the DNA at specific nucleotide sequences (restriction sites)
DNA fragments are separated
-Electrophoresis moves the charged particles through a medium gel by an electric current.
-DNA is separated and transferred onto a membrane by southern blotting
Hybridisation
-Radioactive or fluorescent DNA probes bind to the complementary strands and identify the regions
Evidence
-Radiocative= Xray
-Fluroescent=UV light to give a pattern of bars
