Chapter 15
What did Thomas Hunt Morgan experiment with? What were the dominant and recessive alleles from his experiments? What was unique about his findings?
Morgan experimented with fruit flies.
Red-eyed allele/offspring are dominant and the white-eyed allele/offspring are recessive.
Females never had white eyes. So, the eye color allele has to be on the X chromosome, and there isn’t a corresponding locus on the Y chromosome.
When DNA polymerase reads guanine on the parental strand, what is added to the growing daughter strand?
cytosine
What is the central dogma of biology?
DNA --> mRNA --> proteins
DNA is transcribed into RNA
RNA is translated into proteins
What are the 3 phases of transcription and translation?
initiation, elongation, and termination
What is the basic principle of biology stating that genes are located at specific positions (loci) on chromosomes and that the behavior of chromosomes during meiosis accounts for inheritance patterns?
Chromosomal theory of inheritance
Name the 4 types of chromosomal alterations and briefly explain each.
1. Deletions = when a fragment is lost
2. Duplications = when a fragment is inserted into the sister chromatid
3. Inversions = when a fragment is flipped around
4. Translocations = when a fragment is joined to a non-homologous chromosome
Suppose a double-stranded DNA molecule was shown to have 17% guanine bases. What would be the expected percentages of adenine bases, thymine bases, and cytosine bases in that molecule?
17% cytosine
33% adenine
33% thymine
The genetic code is redundant. What is meant by this?
More than one code can specify the addition of the same amino acid.
(in easier words, 2 or more things gives you the same outcome)
Why are males more likely to be color blind than females?
Color blindness is an X-linked trait. Males only have one X in their genotype, whereas females have 2.
Transcription is the synthesis of RNA using a DNA template.
Translation is the synthesis of a polypeptide using the genetic information encoded in an mRNA molecule.
What is the difference between polyploidy and aneuploidy?
Polyploidy is having more than two complete sets of chromosomes in all somatic cells (3n, 4n, ...)
Aneuploidy is a chromosomal aberration in which one or more chromosomes are present in extra copies or are deficient in number (2n+1, 2n-1)
(Polyploidy will alway be "more"; aneuploidy can be more or less)
When a double helix replicates, each daughter molecule will have one old strand (derived or “conserved” from the parent molecule) and one newly made strand.
What are 3 important types of RNA molecules and their functions?
mRNA carries the genetic information from the DN
rRNA molecules are ribozymes that are integral parts of ribosomes where translation occurs
tRNA converts the codons in the mRNA to the proper amino acid in the polypeptide
What is the main difference between the leading and lagging strand?
The leading strand is synthesized continuously in the 5' → 3' direction, while the lagging strand is synthesized discontinuously in the 5' → 3' direction.
What amino acid sequence will be generated, based on the following mRNA codon sequence?
5'-AUG-UUA-UCU-UUG-3'
Met-Leu-Ser-Leu
List 2 characteristics of Chromosome 21.
1. it is the smallest of the autosomes
2. it is the only autosome that is compatible with life in a trisomy state.
What is the role of DNA polymerase?
It is an enzyme that catalyzes the synthesis of new DNA by adding nucleotides to a preexisting chain.
What are introns and exons?
Introns are the noncoding regions of nucleotides that lie between coding regions are called intervening sequences.
Exons are the regions of nucleotides that are expressed (usually translated into protein).
In regards to size, how does the primary transcript compare to mRNA?
The primary transcript (pre-mRNA) is larger than the mRNA.
The genetic code is essentially the same for all organisms.
An origin of replication is a specific site with a specific sequence of nucleotides.
A replication fork is the site where the DNA strands are being unwound and separated.
What does a lower percentage of recombinants indicate?
It indicates that 2 genes are closely linked
(The farther apart that genes are located on a chromosome the more likely they are to have a crossover events in between them.)
What is meant by the description "antiparallel" regarding the two strands that make up the DNA double helix?
The 5' to 3' direction of one strand runs counter to the 5' to 3' direction of the other strand.
What is alternative splicing?
Alternative splicing can produce proteins with different functions and sizes by adding or removing specific domains.
Why does a new DNA strand elongate only in the 5' to 3' direction during DNA replication?
DNA polymerase can add nucleotides only to the free 3' end.
A gene from an organism can theoretically be expressed by any other organism. Why can we assume this is true?
The genetic code is essentially the same for all organisms.