Exam 4: How do Genes work? Flashcards
How does UV light damage DNA?
It causes thymine dimers to form, which makes kinks in the DNA strand
What are the three ways cancer occurs?
- Random mutations
- Inherited mutations
- Viral infections
What is cancer in 3 words?
Accumulation of mutations
What is the sequence of events in RNA processing?
DNA –> pre-mRNA –> mRNA –> Protein
What process converts DNA to RNA?
Transcription
What process converts RNA to Protein?
Translation
Differences in _______ may cause differences in phenotype
Genotype
How many bases are in a codon?
A group of three bases
Genetic code is redundant - what does that mean?
All but two amino acids encoded by >1 codon
Genetic code is non-overlapping - what does that mean?
Nucleotides belong to only one codon
Genetic code is comma-free - what does that mean?
The codons are read consecutively
Genetic code is conservative - what does that mean?
Codons for the same amino acids are similar
What is the start codon?
AUG
What are the stop codons?
UAG, UAA, UGA
Genetic code is nearly universal - what does that mean?
Codons have the same meaning in all organisms
What is another name for the nontemplate strand?
The coding strand
What is another name for the template strand?
The non-coding strand
What is the ultimate source of all genetic variation?
Mutations
How are mutations good? Bad?
Good: source of genetic variation for evolution
Bad: can cause diseases
Mutation in the hemoglobin-beta gene results in what disease?
Sickle cell disease
In sickle cell disease, glutamic acid is replaced by which amino acid?
Valine
What four things do the effects of mutation on phenotype depend on?
Cell type, when in the life cycle, dominance, type of mutation
What are the three types of mutations?
- Point mutations
- Frameshift mutations
- Chromosome-level mutations
Which mutation results from a single-base change?
Point mutation
Which type of mutation is the largest and results from the addition/deletion of chromosomes?
Chromosome-level mutation
What are the three types of point mutations?
Nonsense, Missense, and Silent
What is a missense mutation?
Changes one amino acid
What is a silent mutation?
Causes no change
What is a nonsense mutation?
Changes to a stop codon
What is a frameshift mutation?
The addition or deletion of a single base
What is the effect of a frameshift mutation?
Changes the whole amino acid sequence
Most mutations are either ____ or slightly ____
neutral or slightly harmful
Chromosome-level mutations involve changes in what?
Chromosome number
What is euploid?
Normal number of chromosomes
What is polyploidy?
3 or more sets of chromosomes
What is aneuploidy?
Having extra or missing chromosomes
What are inversions in chromosomes?
When a segment of a chromosome breaks off then re-attaches but in reverse order
What is translocation in chromosomes?
When a segment of a chromosome breaks off and attaches to a different chromosome
What is a karyotype?
The complete set of chromosomes in an organism
What does ploidy mean?
Set of chromosomes
What is euploid?
Normal number of chromosomes
How many pairs of chromosomes do humans have?
23 pairs
How many sets in diploid?
2 (2n)
How many sets in haploid?
1 (n)
What is one cause of aneuploidy?
Nondisjunction
What is nondisjunction?
Chromosomes do not sort properly during cell division
What are three examples of abnormalities in chromosomes that can still result in survival?
Trisomy 13, 18, 21