24 terms

Biology: 2B (in progress)


Terms in this set (...)

Label DNA molecule
Complementary DNA sequences
DNA to mRNA than to Amino Acids
Amino Acids: Ala Lys Tyr
1. Double helix structure
2. Bases - A, T, G, C
3. Only one type of DNA

1. Usually single-stranded structure
2. Bases - A, U, G, C
3. Three types of RNA (mRNA, tRNA, rRNA)
Define mutation
A mutation is a change in DNA. The two types of mutations are point and frameshift mutations. Point mutations are substitution (less serious replace one letter with another in DNA sequence) and frameshift mutations lose or gain a nucleotide (much more serious cause it affects all codon pairs downstream).
Why are all mutations not bad (w/ example)?
Mutations often produce proteins w/ new and altered functions that can be useful to organisms in different or changing environments. Ex. Lactose tolerant isn't bad because you can drink milk. Also, rock pocket mice mutation from light to dark colored fur.
What is the "central dogma" of biology?
The "central dogma" of biology is the idea that all organisms show similarities because they all use the genetic code table. This shows the possibility that all organisms are descended from a single common ancestor.
What is a frameshift mutation, what causes one, and how can it affect the overall sequence?
A genetic mutation caused by a deletion or insertion in a DNA sequence that shifts the way the sequence is read. A frameshift occurs when a protein is drastically altered, and it is much more serious than a point mutation because a point mutation simply substitutes when letter into another. A frameshift mutation changes the way all the downstream letters are grouped into codons.
How can a mutation be passed onto the next generation?
Cells have to carry that mutation in ovaries or testes else it won't be passed on. This is because when parents egg and sperm cell unite, the fertilized egg receives DNA from both parents which may contain a mutation. If the mutations are presents in the ovaries or testes, they will be present in the parents egg or sperm cells.
What types of mutations will not be passed to the next generation?
Mutations that aren't present in reproductive cells (ovaries or testes) won't be passed on to offspring.
mRNA (messenger)
carries copies of instructions (codons) for the assembly of amino acids into proteins from DNA (in the nucleus) to other parts of the cell
tRNA (transfer)
Carries amino acids to the ribosome and matches them to the coded mRNA message
rRNA (ribosome
It combines with proteins to form ribosomes.
DNA replication picture (focus on helicase and DNA polymerase)
1st step in DNA replication
Initiation - Parent strands are unwound by an enzyme called DNA Helicase.
2nd step in DNA replication
Elongation - Nucleotides must be added in the correct order to create a complementary strand
3rd step in DNA replication
Termination - New strand of DNA is sealed up.
Role of enzymes, helicase and DNA Polymerase, in the process of DNA replication.
Helicase unzips/unwinds the double-helix DNA during replication.

DNA Polymerase is responsible for producing a new strand of DNA. It does this by matching nucleotide bases that are missing when the strand separates.
I can explain the importance of the "redundancy of the genetic code" (w/ ex. from amino acid chart)
There are 64 codons that code for only 20 amino acids. This is a good thing because if there is a small mistake during transcription, there is a chance that through redundancy similar codons could both code for the same amino acids so even though there was a mistake in the base pair sequence, the amino acid sequence may be unaffected.

Ex. All amino acids code for more than one codon, except for Met and Trp. This means if there is a mutation on these codons, the amino acid will likely change.
Missense vs. nonsense vs. silent mutations (point)
Missense - 1 amino acid substituted for another.

Nonsense - Results in a shorter chain because of an early stop codon (UGA).

Silent mutations - No change. Change in a pair but results in a codon that codes for the same or a different amino acid but without any functional changes in the protein product.
The overall process of protein synthesis including DNA, mRNA, tRNA, nucleus, ribosome, amino acid, codon, and anti-codon. Also, include the function of RNA polymerase, the enzyme involved in transcription.
In protein, synthesis there are two main steps: transcription and translation

In transcription, DNA is copied to mRNA, which carries the information needed for protein synthesis. At the end of transcription, the mRNA molecule leaves the nucleus to match with a ribosome. In transcription, an enzyme called RNA polymerase binds to DNA, unzips the double helix, and uses one strand of DNA as a template to assemble nucleotides in to a complementary RNA strand, while also re-zipping the double helix as it forms the complementary base pairs.

In translation, when mRNA molecule is coded into proteins, tRNA molecule has unpaired bases called anticodons which complement one mRNA codon. Once the tRNA anticodon and mRNA codon match, the tRNA drops off an amino acid and as the tRNA exits the ribosome, the amino acid chain repeats until there is a stop codon.
Lac operon picture
I can refer to a picture of the lac operon and can use it to demonstrate my understanding of how prokaryotes regulate gene expression in both the presence and absence of lactose
Lactose Present:
When lactose is present, it binds to the repressor. This causes the release of the repressor which then moves away from the operating region. Transcription can now take place.

Lactose Not Present:
When lactose is not present, the repressor protein binds to the operating region. This blocks RNA polymerase from transcribing the lac genes.
I can use the lac operon as an example to explain why regulation of gene expression is important
Because if lactose isn't present, it is best for the genes to be turned off to conserve the genes anergy and resources.