DNA 1
How does DNA determine the hair color of individuals?
The sequence of DNA determines the structure of proteins which direct genotypes.
Franklin, Watson, and Crick's model of DNA shows a double helix structure where 2 strands of DNA run antiparallel to each other. How does this structure cause the number or purines to equal the number of pyrimidines as observed by Chargaff?
If adenine is on one strand, thymine must be on the other
A strand of RNA has the sequence AUU GCG CGA A. What explanation can be made about how this strand came to be?
The RNA strand was transcribed from a DNA strand with the sequence TAA CGC GCT T.
What evidence would be needed to support an explanation about how RNA is formed from a DNA molecule during protein synthesis?
Evidence would show the original DNA strand and the resulting RNA strand after transcription has occurred.
What is the importance of codons during the process of protein synthesis?
Codons code for the particular amino acids that get assembled.
Which component of DNA replication only occurs on the lagging strand of DNA and not on the leading strand?
An enzyme called ligase binds fragments of DNA together.
Transcription and translation, the two main processes involved in protein synthesis, have distinct molecular inputs and outputs. Which statement about inputs and outputs in these processes is true?
Messenger RNA is an output for the process of transcription and an input for the process of translation.
If a segment of DNA has the sequence of ATCCGA, what would be the complementary mRNA sequence for that segment?
UAGGCU
What external factors can affect gene expression in an organism? Name 3.
a. predation/no
b. temperature
c. amount of light
d. drugs and chemicals
e. genetic makeup of organism/no
A mutation that happens when a single nucleotide is replaced by a different one is called a __________ mutation, also known as a substitution.
point
A mutation caused by the addition of nucleotide into the DNA sequence is known as a _________ mutation This is a type of __________ mutation because it causes a change in the reading frame of the DNA.
insertion, frameshift
Match the different types of RNA with the role they play in protein synthesis. (mRNA, rRNA, tRNA)
1. _____ forms subunits of ribosomes
2. _____ carries amino acids to ribosomes
3. _____ carries transcribed code for a protein
1. rRNA
2. tRNA
3. mRNA
Name one way that DNA replication and transcription are similar.
Both DNA replication and transcription require an enzyme to help unwind the chromosome.
A student studies the role of promoters in two groups of organisms (photosynthetic prokaryotic cyanobacteria and photosynthetic eukaryotic brown algae). What observation should the student have made?
The promoter is the DNA sequence that aids in transcription in both groups of organisms.
A student compares the process of gene expression in 2 groups of organisms. (eukaryotic brown algae and prokaryotic cyanobacteria). a. What difference should the student observe?
b. and which expression best describes how cyanobacteria regulate expression of genes in prokaryotic cells?
a. Transcription in the brown algae occurs in the nucleus, but in the cyanobacteria, it occurs in the cytoplasm.
b. by limiting transcription
Erwin Chargaff found that different species have similar ratios of purines to pyrimidines in their DNA. What conclusion was made from this scientific discovery?
That DNA bases pair according to rules. (Chargaff's Rules!!)
Name two statements that would be true about a model of RNA and a model of DNA?
1. DNA is double-stranded , while RNA is single stranded.
2. DNA uses deoxyribose as its sugar, while RNA uses ribose as its sugar.
Rosalind Franklin took x-ray photographs of DNA that showed an X surrounded by a circle. What was the conclusion of this scientific discovery?
That DNA is shaped like a double helix.
Name 2 ways that DNA replication and transcription are different.
1. DNA replication produces DNA, but transcription produces RNA.
2. DNA replication copies all of the chromosome while transcription copies only the part of the chromosome that has genes.
Are the following statements about gene expression true or false?
a. It is the activation of certain genes at certain times that causes cells to differentiate.
b. Cells turn off particular genes when they are no longer needed for the cells to function.
c. The cyanobacteria perform cell differentiation at a much higher level than the brown algae.
d. It is the removal of certain genes from an organism that causes its cells to become differentiated.
a. true
b. true
c. false
d. false
Number the following steps from 1-5 to show how DNA replication errors are handled.
DNA polymerase detects an error in replication___
DNA polymerase takes in a single strand of DNA and adds the matching nucleotides to make double-stranded DNA _____
Errors have been limited and replication continues until the entire strand has been copied. ____
Replication is halted _____
DNA polymerase removes the incorrect nucleotide and replaces it with the correct one.
2, 1, 5, 3, 4
Number the steps from 1 to 5 to show the correct sequence of translating a protein.
___ A newly synthesized mRNA molecule is released from the nucleus.
_____ The ribosome encounters one of 3 stop codons that triggers the release of the newly synthesized polypeptide chain.
_____ A ribosome bonds to the mRNA molecule and protein synthesis is initiated at the start codon.
_____A tRNA amino acid complex enters the codon next to the start codon. Base pairing occurs, and the two amino acids are linked.
_____ The ribosome moves one codon forward, making space for a new tRNA amino acid complex to enter, and the process repeats.
1
5
2
3
4
What scientific discovery did Oswald Avery make when he observed DNA being destroyed and bacterial transformation not occurring? This is also the same discovery made when Hershey and Chase found in their experiment when bacteria are infected by bacteria, phosphorus from viral DNA remains in bacteria.
That DNA is the hereditary material.
Two mutations occur in the same gene. One of the mutations involves a single nucleotide being inserted into the gene. The second mutation involves a single nucleotide replacing a different nucleotide. For each mutation, explain how the mutation may affect the protein that the gene codes for and predict which mutation is more likely to prevent the protein from being able to function properly.
If the DNA sequence is mutated, mRNA will code for a mutant protein with a different structure
The insertion mutation would be more likely to disrupt the function of the protein because it causes a shift in the reading frame.
Describe the structure of DNA in terms of nucleotides, covalent bonds, sugars, phosphates, bases, and hydrogen bonds.
The covalent bonds connect the sugars and phosphates in the backbone of the DNA molecule, and the rungs of the helix (ladder) are made of the nucleotide bases (A,C, T, G) held together by hydrogen bonds