General Flashcards
When examining inherited differences in drug responses, what two factors should be considered?
drug efficacy and adverse drug reactions
Three main types of RNA are involved in protein synthesis.
They aremessenger RNA (mRNA), transfer RNA (tRNA), and ribosomal RNA (rRNA). rRNA forms ribosomes, which are essential in protein synthesis.
Nondisjunction
Is the failure of the chromosomes to separate, which produces daughter cells with abnormal numbers of chromosomes.
What is cohesin?
A protein glue that holds the daughter chromosomes together.
Symptoms of cystic fibrosis include:
recurring chest infections
wheezing, coughing, shortness of breath and damage to the airways (bronchiectasis)
difficulty putting on weight and growing
yellowing of the skin and the whites of the eyes (jaundice)
diarrhoea, constipation, or large, smelly poo
a bowel obstruction in newborn babies (meconium ileus) – surgery may be needed
Gene regulation is complex…
genes can be regulated at many points
1.Transcription
2.post-transcription
3. post-translational
Measuring gene expression levels
-quantitive PCR - good for 10-100s genes
-microarray - good for thousands of genes
-RNAseq - good for assaying the entire genome
What are daughter chromosomes?
The chromosomes that result from replication.
What 2 things occur in Prophase of mitosis
1) The nuclear membrane breaks apart.
2) Proteins package the paired chromosomes into shorter and thicker rods (CONDENSATION).
What is condensation, in terms of protein involvement?
Proteins package chromosomes into shorter thicker rods.
Symptoms of cystic fibrosis include:
-recurring chest infections
-wheezing, coughing, shortness of breath and damage to the airways (bronchiectasis)
-difficulty putting on weight and growing
-yellowing of the skin and the whites of the eyes (jaundice)
-diarrhoea, constipation, or large, smelly poo
-a bowel obstruction in newborn babies (meconium ileus) – surgery may be needed
A BCR-ABL1 genetic test
uses a sample of blood or bone marrow to look for an abnormal gene called BCR-ABL1. This abnormal gene is involved in certain types of blood cancer. It’s found in: Most people who have chronic myeloid leukemia (CML), which is also called chronic granulocytic leukemia or chronic myeloid leukemia.
Huntingtons’s Diease
-dominant
-disruption of brain chemistry which leads to cellular death
-muscular twitching
-emotional disturbances
-chromosome #4 marker
Porphyria
-dominant
-can not metabolize RBC breakdown
-causes neurological problems
-sun exposure can cause skin to blister
Describe the molecular basis for Sickle Cell Anaemia
-SCA is caused by a single DNA mutation, an A to a T in the beta-globin gene
-Glutamate changes to valine in the amino acid chain
Identify the symptoms of Sickle Cell Anaemia
Anaemia
Fever
Severe pain
Sudden death
Describe the treatment for Sickle Cell Anaemia
Treatment usually aimed to limit symptoms and complications
Both beta globin proteins need to be mutated to cause Sickle cell anaemia.
What does this tell us about the disease?
Autosomal recessive inheritance
What is sickle cell trait?
-Sickle cell trait is a milder form of sickle cell anaemia wherein individuals are heterozygous for the mutation.
-Increases resistance to malaria.
Discuss the geographical variation with sickle cell anaemia
-SCA is very rare in non-African populations and common in populations with African ancestry
-Similarity in distribution across populations with malaria endemicity
What is epigenetics?
Epigeneticsis the study of heritable changes in gene expression that does not involve changes to the underlying DNA sequence
What is Huntington’s disease?
Huntington’s Disease in an inherited neurodegenerative disease, involving the death of brain cells
Identify 4 symptoms of Huntington’s Disease
-Seizures
-Abnormal gait
-Personality change
-Dementia
Describe the molecular basis for Huntington’s disease
Mutation is a short tandem repeat (STR)
What pattern of inheritance does Huntington’s disease follow?
Autosomal dominant inheritance
How can Huntington’s Disease be detected?
DNA test detection: use a polymerase chain reaction (PCR) to amplify the CAG repeat
In terms of Huntington’s disease, what is meant by the term anticipation?
-Age of onset commonly 40-50 (varies)
-Anticipation is when the age of onset becomes earlier and symptoms become more severe from generation to generation
How can age of onset be determined in Huntington’s disease?
-Age of onset is affected by CAG repeat length
-However, there is still a lot of variation as the influence of the age of onset is multifactorial
Identify two approaches in which Huntington’s Disease can be treated
We all have the HTT gene and it is turned on in all cells:
Appproach 1: use a suppressor screen – delete every gene in turn and identify genes that, when deleted, prevent HD.
Approach 2: chemical inhibition of kynurenine biochemical pathway
What are developmental disorders?
Developmental disorders are a group of psychiatric conditions originating in childhood that involve serious mental and physical impairment in different areas
What is a pedigree chart?
A pedigree is a diagram showing genetic information from a family, using standardized symbols.
State 2 purposes of a pedigree chart
-Determines whether the pattern of inheritance for a given trait
-Discovers whether the gene in question is located on an X or Y chromosome or an autosome
Why is it important to establish how a trait is inherited?
State 3 reasons
If the pattern of inheritance can be established, it can be used to predict genetic risk in several situations, including:
Pregnancy outcomes
Adult-onset disorders
Recurrence risks in future off spring
What is a codon?
Codons are triplets of nucleotides in mRNA that encode the information for a specific amino acid in a protein
What is a stop codon?
Stop codons are codons in mRNA that signal the end of translation (end of protein synthesis)
Pedigrees use a standardised set of symbols.
How are males and females represented?
Squares represent males
Circles represent females
Pedigrees use a standardised set of symbols.
How are affected individuals represented?
Individuals with the phenotype in question is represented by a filled-in symbol
Pedigrees use a standardised set of symbols.
How are heterozygotes represented?
Heterozygotes, when identifiable, are indicated by a shaded dot or a half-filled symbol
Pedigrees use a standardised set of symbols.
How are individuals represented when their sex is unknown?
If the sex of a person is unknown, a diamond is used
Pedigrees use a standardised set of symbols.
How are romantic relationships represented?
Parents are connected by a horizontal line
Closely related parents (such as first cousins) are connected by a double line
Divorced parents are connected by a horizontal line with slanted lines
Identify 3 unique features of autosomal recessive inheritance
All the children of two affected (homozygous) individuals are affected
The risk of an affected child from two heterozygote parents is 25%
For rare traits, affected individuals have unaffected parents
Identify a non-Mendelian pattern of inheritance
Mitochondrial inheritance - traits controlled by single genes coded for by mitochondrial genes
What can be expected with traits on autosomes (non-sex chromosomes)?
Expressed in both males and females (affected in roughly equal numbers)
Both the male and the female parent transmit the trait
Identify 6 different diseases with autosomal recessive inheritance
Albinism
Cystic fibrosis
Phenylketonuria
Sickle cell anaemia
Thalassemia
Xeroderma pigmentosum
Identify 3 stop codons
UAA
UAG
UGA
What is a start codon (AUG)?
A start codon is always the first codon in a gene, present in mRNA to signal the location for translation to begin.
AUG = methionine
What is a start codon (AUG)?
A start codon is always the first codon in a gene, present in mRNA to signal the location for translation to begin.
AUG = methionine
How is genetic code written?
Genetic code is written as it appears in an RNA copy of the DNA template
What is transcription?
Transcription is the first step of gene expression, in which a particular segment of DNA is copied into RNA (especially mRNA) by the enzyme RNA polymerase.
Identify the 3 stages in transcription
-Initiation
-Elongation
-Termination
Describe initiation in transcription
Initiation: RNA polymerase binds to a specific nucleotide sequence (called a promoter) that marks the beginning of a gene.
Describe elongation in transcription
Elongation: DNA strands unwind, and RNA polymerase reads the nucleotide sequence of the template strand.
As it moves along, it inserts and pre-mRNA molecule.
Describe termination in transcription
Termination: RNA polymerase reaches the end of the gene, marked by nucleotides called a 3’ termination sequence
-RNA-polymerase stops adding nucleotides to pre-mRNA which falls off the DNA template strand and is released
-DNA strands re-form a double helix
What is an intron?
An intron is a sequence in the pre-mRNA molecule that is not transcribed