Genetics Final: Midterm 1 Questions Flashcards
Heat can disrupt hydrogen bonding between DNA strands. Which of the following DNA strands would denature at the HIGHEST temperature?
Whichever one has the largest number of GC bonds.
This is due to the fact that GC are connected by 3 hydrogen bonds unlike AT which are connected by 2 hydrogen bonds.
This means it takes more energy and a higher temperature to denature strands with more GC bonds.
If a DNA molecule contains 17% guanidine bases (G), then what percentage of thymine bases will it have?
33%
Because G binds to C they have equal amounts.
So 17 + 17 = 34
100 - 34/2 = 33
So there are 33% of each Thymine and Adenine within the molecule.
If the sequence of one strand of DNA is
5’ -GCTAGCGTCG-3’,
what is the sequence of the complementary strand?
3’-CGATCGCAGC-5’
All DNA polymerases synthesize new DNA by adding nucleotides to the ____ of the growing DNA chain.
3’ OH
Know the DNA replication fork.
:)
What is the function of telomerase?
Adds repetitive DNA to protect chromosome ends
What is the function of DNA polymerase I?
Removes RNA primer and replaces DNA
What is the function of DNA polymerase III?
Synthesizes most of the new DNA strand
What is the function of RNA primase?
Synthesizes a fragment of RNA to initiate synthesis
What is the function of DNA ligase?
Glues fragments of single-stranded DNA together
Which of the RNAs have the message for an encoded protein?
mRNA
Which of the RNAs carry free amino acids to the ribosome?
tRNA
Which is a true statement regarding transcription in most organisms?
Different genes may be transcribed from different strands of DNA.
Where are promoters usually located?
Upstream of the start site
In transcription, where are new nucleotides always added onto the growing DNA chain?
The 3’ OH
Which of the following statements about RNA polymerase is NOT true?
RNA polymerase reads a template strand of DNA 5’ to 3’
All of the following are true statements regarding RNA polymerase:
- RNA polymerase adds a ribonucleotides to the 3’ end of a growing RNA molecule.
- RNA polymerase binds to a promoter to initiate transcription
- During transcription of a gene, RNA polymerase reads only one strand of DNA.
- RNA polymerase has many subunits
If the DNA strand 5’-GTACCGTC-3’ were used as template for transcription, what would the sequence of the transcribed RNA?
5’-GACGGUAC-3’
If the sequence of an RNA molecule is 5’-GGCAUCGACG-3’, what is the sequence of the coding strand of DNA?
5’-GGCAUCGACG-3’
Go over question 20 on paper.
:)
In eukaryotic cells, where do “specific” transcription factors bind?
The regulatory promoter and the enhancer.
What would the consequence by of a two nucleotide-deletion mutation in the middle of the first exon of a protein-coding gene?
A reading frameshift would occur. All codons (and thus amino acids) downstream of the codon in which the deletion occurred would be different including the stop signal.
Be able to read codon charts and interpret them.
:) refer to questions 23-24 on the first exam.
Haploid cells are cells with _____ chromosomes.
A single set.