What are promoter regions of DNA?
Gene regulatory elements that tell RNA polymerase to perform transcription.
Gene regulatory elements that tell DNA polymerase to perform transcription.
Gene regulatory elements that tell RNA polymerase to perform translation.
Gene regulatory elements that tell DNA polymerase to perform translation.
Transcription factors bind to regulatory sequences and cause what?
Recruitment of RNA polymerase
Recruit of DNA polymerase
What does the green question mark represent?
Nucleosome
Chromosome
Telomere
Promoter region
The green arrow is pointing to what?
Linker DNA
Core DNA
The nucleosome is made up of what components?
Histone octamer of H2A, H2B, H3 and H4.
Histone tetramer of H2A, H2B, H3 and H4.
SRY is a transcription factor on the Y chromosome. It's absence/mutation leads to...?
Absence of the male phenotype, leading to production of a female phenotype.
Absence of the female phenotype, leading to production of the male phenotype.
The Y gene of the XY male genotype is gene-poor. What are two dosage compensation mechanisms that could help to equal gene expression levels in both males and females.
Upregulation of transcription of the X male chromosome
Inactivation of one of the X female chromosomes
Addition of an extra X chromosome in the male XY genotype
Epigenetics produces multiple phenotypes from the same genotype.
Diploid cells have a single copy of an allele.
Autosomal conditions are genetic conditions that occur on non-sex chromosomes.
An X-linked condition will only affect the phenotype of a female if the copies of the allele on each X chromosomes are abnormal.
Achondroplasia (dwarfism) is what type of condition?
Autosomal dominant
Autosomal recessive
Albinism is what type of condition?
How might a child have achondroplasia despite the parents not having it?
Parent(s) are carriers
Paternity (social father)
Mutation in sperm/egg
How can two parents that have albinism have a child without albinism?
Albinism is autosomal recessive. This means that any child born to parents who both have albinism should also have albinism as there are no dominant traits in the parents as their genotypes are both homozygous recessive. The reason for the absence of albinism is because the mutated copies in the parents could differ in that the fathers two copies could inhibit a different enzyme in the metabolic pathway that leads to lack of pigment than the mothers. The child will inherit one copy from the father and one copy from the mother and therefore only 50% of each originally fully mutated pathway is inhibited and thus may still be able to produce sufficient melanin.
Albinism is autosomal dominant. This means that any child born to parents who both have albinism should also have albinism as there are no dominant traits in the parents as their genotypes are both homozygous dominant. The reason for the absence of albinism is because the mutated copies in the parents could differ in that the fathers two copies could inhibit a different enzyme in the metabolic pathway that leads to lack of pigment than the mothers. The child will inherit one copy from the father and one copy from the mother and therefore only 50% of each originally fully mutated pathway is inhibited and thus may still be able to produce sufficient melanin.
Haemophilia results in blood clotting problems due to factor 7 deficiency.
Females are more likely to suffer from haemophilia
Phenylketonuria is a disorder resulting from the production of phenylketones due to mutation in what enzyme?
Phenylalanine hydroxylase
Carbonic anhydrase
Phenylalanine anhydrase
Tyrosine hydroxylase
What are some causes of variation?
Selection pressure
Genetic drift
Founder effect
Bottleneck
Ethnic group selection (HbS)
How many pairs of autosomal chromosomes do most humans have?
22
1
23
46
44
Mitosis is important for what?
Growth
Repair
Tumour growth
Spermatogenesis
Oogenesis
What is crossing over?
Exchange of genetic information between homologous pairs of chromosomes which produces recombinant chromosomes.
The random assortment (lining up) of chromosomes that end up in the gametes.
What is independent assortment?
When does independent assortment occur?
First meiotic division
Second meiotic division
Chromosomal non-disjunction describes the failure of homologous chromosomes to seperate in the first or second division in meiosis or during mitosis.
Chromosomal non-disjunction can lead to trisomy of sex chromosomes.
The following picture shows the process of meiosis in males
The following picture shows chromosomal non-disjunction of the...
First division
Second division
The following picture shows chromosomal non-disjunction during female meiosis.
Meiotic non-disjunction occurs pre-embryonically and therefore all cells are effected.
Mitotic non-disjunction occurs during embryonic division so there may be a mix of normal and abnormal cells, resulting in an abnormal conceptus.
How does trisomy 21 (aka Down's) occur?
One copy of the mother's C21 translocates to C14. Upon fertilisation, the future child will have inherited two copies from the mother (due to the translocated C21 to C14 as well as the normal C21 copy) and a copy from the father, making 3 copies of C21.
The mother is a carrier of three C21 copies which leads to the child inheriting two copies of C21 from the mother and one from the father.
C14 changes into C21 upon fertilisation, therefore two copies are inherited from mother/father and one other copy from the father/mother.
Mutations are frequently due to...
Copying errors during DNA replication
Spontaneous depurination
Background ionising radiation
Chromosomal non-disjunction
Splicing errors
A transcriptional mutation commonly affects the promoter region of a gene, therefore promotion to initiate transcription does not occur and thus a protein is not produced.
A splice site mutation (deleted/creation of splice site) does not introduce introns into the mature mRNA transcript.
Common gene mutations are indicated in certain cancers.
What is the function of the mismatch repair machinery?
The mismatch repair machinery helps to repair slippaged DNA (insertion/deletions) that escapes proofreading
The mismatch repair machinery helps to destroy cancer cells
The mismatch repair machinery helps to repair incorrectly paired DNA strands
Sickle cell is caused by a substitution of hydrophilic valine for hydrophobic glutamate (GAG -> GTG)
Cystic fibrosis is caused by deletion of a codon coding for a phenylalanine residue of the CFTR channel protein.
PCR are repeated cycles of...?
Primer, Polymerase, Denaturation.
Polymerase, Primer, Denaturation.
Denaturation, Polymerase, Primer.
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