Cellular Control & Patterns of Inheritance Flashcards
What is chromosome mutation?
A change in the number or sequence of genes on a chromosome.
What are the 4 types of chromosome mutation?
- Duplication
- Deletion
- Translocation
- Inversion
What is a translocation chromosome mutation?
when a section of a chromosome breaks off and attaches to a different chromosome.
What is an inversion chromosome mutation?
when a section of a chromosome breaks off and attaches to the same chromosome, but is inverted.
What is meant by post-transcriptional control?
modification of pre-mRNA to produce mature mRNA.
What are introns?
sections of non-coding RNA or DNA.
What is meant by post-translational control?
modification of mRNA after they have been synthesised.
What is the name of the compound used in cells to add a phosphate group to a protein?
cAMP.
What is the function of homeobox genes?
to act as regulatory genes which control the expression of genes involved in growth and development.
What are highly conserved genes?
genes which show very little mutation and are very similar between diverse groups of organisms.
What are Hox genes?
the group of homeobox genes that control the body plan in animals.
Which two cellular processes are important for the morphology (shape) of organisms?
mitosis & apoptosis.
What is chlorosis?
the production of too little chlorophyll, making leaves appear yellow.
What are 3 environmental factors that cause chlorosis?
- insufficient sunlight
- mineral deficiency
- viral infections
How does sexual reproduction lead to genetic variation?
- random mating
- random fertilisation
- recombination between homologous chromosomes during meiosis
What is monogenic inheritance?
the inheritance of a single gene.
What is codominance?
equal dominance between two alleles, resulting in both alleles being expressed in the genotype.
What is a sex linked gene?
a gene located on a sex chromosome.
What is autosomal linkage?
when both alleles occur on the same chromatid so the alleles are inherited together unless crossing-over occurs.
What is epistasis?
the interaction between different genes, where the expression of one gene is affected by the expression of another gene at a different locus.
What process leads to the appearance of new alleles of a gene?
mutation.
What is meant by the term gene pool?
the total number of different genes present in an interbreeding population.
What is meant by the term gene flow?
the movement of genes from one population to another.
What is meant by the term genetic drift?
a change in the allele frequency of a population due to chance.
What are the 3 levels of control of gene expression?
- transcriptional
- post-transcriptional
- post-translational
How can gene expression be controlled at a transcriptional level?
by altering the rate of transcription of genes (which is controlled by transcription factors).
What are transcription factors?
proteins that bind to DNA and switch genes on and off by increasing or decreasing the rate of transcription.
What are transcription factors that increase the rate of transcription called?
activators.
What are transcription factors that decrease the rate of transcription called?
repressors.
Where do transcription factors bind in prokaryotes, to control gene expression?
operons.
What is an operon?
a section of DNA that contains a cluster of structural genes, that are transcribed together, as well as control elements, and sometimes a regulatory gene.
What do control elements include?
- promoter
- operator
What is a promoter?
a DNA sequence located before the structural genes that RNA polymerase binds to.
What is an operator?
a DNA sequence that transcription factors bind to.
What 3 structural genes does a lac operon have?
- lacZ
- lacY
- lacA
What occurs in a lac operon when lactose is present?
- lactose binds to the repressor, changing the repressor’s shape so it can no longer bind to the operator site.
- RNA polymerase can now begin transcription of structural genes.
What occurs in a lac operon when lactose isn’t present?
- the regulatory gene (lacI) produces the lac repressor, which is a transcription factor that binds to the operator site when there’s no lactose present.
- this blocks transcription because RNA polymerase can’t bind to the promoter.
What are primary mRNA transcripts?
mRNA strands containing introns and exons.
What is splicing?
the process where introns are removed from primary mRNA strands to form mature mRNA strands (happens in the nucleus).
What does cAMP do at the post-translational level?
- protein activation molecules can bind to cell membranes and trigger the production of cAMP in the cell.
- cAMP activates proteins in the cell by altering their 3D structure (e.g: change the active site of an enzyme).
What is a body plan?
the general structure of an organism.
What are Hox genes?
genes that code for the proteins that control body plan development.
What is the homeodomain?
a protein that binds to specific sites on DNA, enabling the protein to work as a transcription factor.
What is codominance?
when both alleles are expressed in the phenotype, neither one is recessive.
What does the phenotypic ratio 3:1 (dominant : recessive) in the F2 generation indicate about the type of genetic cross?
it’s a monogenic cross (e.g: RR x rr).
What does the phenotypic ratio 9:3:3:1 in the F2 generation indicate about the type of genetic cross?
it’s a dihybrid cross (e.g: RRYY x rryy).
What does the phenotypic ratio 1:2:1 in the F2 generation indicate about the type of genetic cross?
it’s a codominant cross (e.g: H^N H^N x H^S H^S)
What are 2 examples of X-linked disorders?
- colour blindness
- haemophilia
How do you know if your calculate value is significant or not (e.g: in a chi squared test)?
if the calculated value is larger than the critical value, then it is significant.
