Unit 6: Gene Expression and Regulation
List 3 differences between DNA and RNA.
1.) Different sugars: deoxyribose for DNA, ribose for RNA 2.) Double stranded (DNA) vs. single stranded (RNA) 3.) DNA contains thymine, RNA contains uracil; both pair with adenine
The DNA from a certain plant species is analyzed. The DNA contains 22% thymine. Determine the percent of the other bases.
22-thymine, 22-adenine 28-cytosine, 28-guanine
An mRNA sequence reads: 5'- CGAUGCAGA- 3'. Translate this sequence
3'-GCTACGTCT-'5
A section of the template strand of DNA reads: 5'-CAACACTAA- 3'. Determine the mRNA sequence and translate it.
3'-GTTGTGATT-5'; Gin, His, ?
If one DNA strand reads: 3'- ACTAG -5' what would the complementary DNA strand read?
5'-TGATC-3'
Explain how this bundle of cells eventually forms a human with specialized cells
?
If a bacterial cell uses up its tryptophan storage, what would happen to the trp operon?
?
True or false: the genetic code is read in groups of two nucleotides at a time called the doublet code.
?
Describe the process of transduction.
A bacteriophage passes DNA from one bacteria cell to another (transfer of DNA from one cell to another via a viral vector)
What is the center of DNA composed of?
A five carbon sugar, a phosphate molecule, and four nitrogenous bases
Describe transformation.
Bacteria absorb DNA from their surroundings and incorporates it into their genome
Identify the major classes of macromolecules and then identify their monomers and polymers.
Carbohydrates: monosaccharides (m) and polysaccharides (p) Lipids: glycerol (m) Proteins: amino acids (m) polypeptides (p) Nucleic acids: nucleotides (m)
Fill in the blank: the mRNA nucleotide triplets are called _________. These code for ________ _________.
Codons; specific amino acids
Where does translation occur?
Cytoplasm
Describe the process of conjugation.
DNA transfer from one bacterium to another
Describe the mutation that causes cystic fibrosis.
Deletion of phenylalanine on amino acid 508
Describe step-by-step how DNA is replicated.
Double helix is opened and strands are separated, template strand is primed, DNA is assembled on the segment, strands uncoil
True or false: only the template strand of DNA is transcribed during transcription.
False
Differentiate between histone acetylation and DNA methylation.
Histone: formation of heterochromatin Methylation: long-term repression
Differentiate between a repressible and inducible operon.
Inducible; Turned on by presence of small molecule Repressible; Turned on y default
Describe the consequences of a chemical that prevents the 5' cap and poly-A tail from forming on eukaryotic mRNA?
It can lead to degradation of the mRNA
What does it mean if a gene/trait is "evolutionarily conserved"?
It has basically stayed the same through evolution
Why is redundancy in the genetic code important?
It minimizes harmful effects from mistakes in the sequence
Is DNA positively or negatively charged? How could you tell just by looking at a strand of DNA?
It's negatively charged
Which amino acid does this tRNA carry?
Methionine
How can mutations lead to natural selection?
Natural selection decides which mutations stay and which die out
In eukaryotic cells where does transcription occur?
Nucleus
The very first tRNA will enter at which site on the ribosome (A, P, or E)?
P site
Fill in the blank: A change in an organism's genotype can cause a change in the organism's_________.
Phenotype?
What are the three parts of an operon?
Promoter, operator, and structural genes
If an error occurs in DNA replication, how is it fixed?
Proofreading or mismatch repair
Differentiate between purines and pyrimidines.
Purines: adenine and guanine pyrimidines: cytosine and thymine
In which stage of the cell cycle does DNA replicate?
S phase
Differentiate between silent, missense, and nonsense mutations.
Silent; nucleotide base is changed missense; ? nonsense; change to stop codon
What is the codon that the tRNA binds to?
Start codon
What does it mean that DNA strands are antiparallel and complementary?
Strands run in opposite directions and the base pairings are complementary to each other
What is the backbone of DNA composed of?
Sugar and phosphate
What functional group defines the 3' end of DNA?
Terminal hydroxyl group
What does it mean that DNA strands are antiparallel?
The beginning of one strand matches up with the end of the other strand
Describe the Meselson and Stahl experiment that supported the semi-conservative model of DNA replication.
The strands separate and copy themselves so the daughter strands get old and new strands
What functional group defines the 5' end of DNA?
The terminal phosphate group
What role do cytoplasmic determinants play in early embryonic development?
They are responsible for regulation of gene expression in the embryo
Why do introns exist if they are just spliced out of the mRNA during pre-mRNA modifications?
They exist to be cut out so that the protein is placed in the correct place
Describe how it is possible for only one identical twin to express an inherited disease.
This is possible because twins are genetically different
Fill in the blanks: protein synthesis occurs in two stages _______ and _________.
Transcription and translation
List and describe the steps of transcription.
Transcription takes place in the nucleus of the cell. During transcription messenger RNA (mRNA) reads and copies DNA's nucleotide sequence in the form of a complimentary RNA strand. Then the mRNA carries the DNA's information in the form of codons to the ribosome. Codons are a 3 nucleotide sequence in an mRNA strand.
Fill in the blanks: The process of ________ converts DNA to RNA. The process of ______ turns RNA into proteins.
Transcription, translation
Fill in the blanks: tRNA has an ________ region which is complementary and antiparallel to _______.
Trinucleotide?
True or false: plasmids replicate separately from chromosomal DNA.
True
Using a codon chart determine what UAU codes for?
Tyr
Are promoter regions upstream or downstream of the gene?
Upstream
When does translation stop?
When it reaches a stop codon
