Week 3- Genes And Genomes Flashcards
What percentage of DNA is coding DNA?
~ 1.5% of DNA is coding DNA
What constitutes the remaining ~ 98.5% of DNA?
Non-coding DNA, which includes functionally important elements like enhancers and promoters, as well as genes that produce RNAs such as ribosomal and transfer RNAs
What are the components of a eukaryotic gene?
Coding exons separated by non-coding introns
What is the function of spliceosomes?
Perform RNA splicing
What is a characteristic of ~ 10% of protein-coding genes?
They have a single exon that does not undergo splicing
What process generates haploid gametes from diploid parents?
Meiosis
What happens during crossing over in meiosis?
Homologous chromosomes exchange genetic material
What is the result of meiosis II in primary spermatozoa?
It gives rise to haploid secondary spermatozoa, generating unique genetic combinations
What are genes considered in genetics?
Hereditary ‘units’
What are alleles?
Different versions of a gene, such as R and r for a specific trait
What is the significance of the lacZ gene in E. coli?
It produces the enzyme beta-galactosidase when lactose is present
What role does the repressor protein play in gene expression?
It binds to the promoter region of the lacZ gene, blocking RNA polymerase from transcribing the gene
What occurs when the repressor protein binds to lactose?
It changes conformation and detaches from the promoter, allowing transcription to proceed
What elements are necessary for a transgene to function properly in a new organism?
A promoter sequence and a terminator sequence
What is the most common promoter element used in genetically modified organisms?
CaMV35S promoter derived from the cauliflower mosaic virus
What is the purpose of PCR in DNA analysis?
To amplify host DNA for observation
What happens to DNA when heated to around 95°C?
The hydrogen bonds between complementary bases break
What is the role of cytokinesis in meiosis?
It segregates the two chromosome sets into different germ cells
Fill in the blank: Genes are hereditary ‘units’ that lead to _____ being inherited.
phenotype
True or False: All life shares DNA as a hereditary molecule.
True
What is required to synthesize new strands of DNA from template strands?
Primers are required that are short sequences of DNA complementary to the base sequences either side of the region of interest.
What is the forward primer sequence in the given DNA synthesis process?
5’ – CGATCTGATATGCC – 3’
What is the reverse primer sequence in the given DNA synthesis process?
5’ – AGACAGACAGGATA – 3’
What temperature needs to be achieved for primers to anneal to their complementary bases?
The temperature needs to cool down from 95°C to around 5°C.
What are the free dinucleotide triphosphate molecules needed for DNA synthesis?
dATP, dGTP, dCTP, and dTTP molecules.
Which polymerase enzyme is mentioned for DNA synthesis?
Taq polymerase.
What is the optimal temperature for the polymerase enzyme to extend the primers?
The optimal temperature is 72°C.
What happens at the end of one cycle of the DNA synthesis process?
Two newly synthesised, complementary strands have been added.
What is the initial template strand count before repeating the DNA synthesis cycle?
4 template strands.
At what temperature should the double helix be heated to denature during the DNA synthesis process?
Heat up to 95°C.
Fill in the blank: To synthesize new strands of DNA, short sequences of DNA called _______ are required.
primers
True or False: The forward primer sequence is 5’ – AGACAGACAGGATA – 3’.
False
What is the purpose of ligating free dinucleotide triphosphate molecules?
To attach them to the 3’ (-OH) end of the primers.
What is the process of cooling the temperature to allow primers to anneal called?
Annealing.
What is the result of the polymerase enzyme’s action during DNA synthesis?
It extends the primers.
What are the two stages of temperature changes during the DNA synthesis cycle?
Denaturation and annealing.
What does PCR stand for?
Polymerase Chain Reaction
What is the purpose of PCR?
To amplify DNA sequences
What is the first step in the PCR process?
Denaturation at high temperature
At what temperature does denaturation occur in PCR?
Approximately 94-98°C
What happens during the annealing step of PCR?
Primers bind to the DNA template
At what temperature does the annealing step typically occur?
Around 50-65°C
What is the role of primers in PCR?
To initiate DNA synthesis
What is the temperature range for the extension step in PCR?
72°C
What enzyme is primarily used in the extension step of PCR?
DNA polymerase
What is the significance of the temperature 72°C in PCR?
Optimizes temperature for polymerase enzyme activity
True or False: The quantity of DNA sequences doubles with each cycle of PCR.
True
Fill in the blank: The DNA can be dyed and run out on an _______.
agarose gel
What is the typical room temperature for PCR setup?
Room temperature
What are the three main steps of a single PCR cycle?
- Denaturation
- Annealing
- Extension
What is the function of the PCR process in molecular biology?
To create millions of copies of a specific DNA segment
What happens to the DNA template number after each PCR cycle?
It increases exponentially
What is the significance of cooling to 5°C in PCR?
Allows primers to anneal to the DNA template
What is the function of the denaturation step in PCR?
To separate the double-stranded DNA
What is the temperature during the annealing phase?
Cool to approximately 55-65°C
Fill in the blank: The sequence of DNA is complementary to the _______.
template strand
What is the role of agarose gel in DNA analysis?
To visualize DNA after amplification
What happens to the amplification efficiency of DNA in PCR?
It is not strictly exponential due to various factors
Fill in the blank: The DNA sequence is synthesized in the _______ direction.
5’ to 3’
