final-new material Flashcards
Which of the following is true about a plant with the genotype AABbcc?
- It is homozygous at two loci.
- It has recessive alleles at three loci.
- It is heterozygous at two loci.
- It will not express the recessive c allele.
It is homozygous at two loci.
Mendel’s observation of the segregation of alleles in gamete formation has its basis in which of the following phases of cell division?
anaphase 1 of meiosis
Mendel’s second law of independent assortment has its basis in which of the following events of meiosis I?
alignment of tetrads at the equator
When constructing a Punnet square, the symbols on the outside of the boxes represents ______, while those inside the boxes represent ______.
gametes, progeny
A sexually reproducing animal has two unlinked genes, one for head shape (H) and one for tail length (T). Its genotype is HhTt. Which of the following genotypes is possible in a gamete from this organism?
HT
How many genetically unique types of gametes could be produced by an individual with the genotype RrYY?
2
True or false, the same phenotype can be produced by more than one genotype.
true
Mendel accounted for the observation that traits that had disappeared in the F1 generation reappeared in the F2 generation by proposing that _____.
traits can be dominant or recessive, and the recessive traits were obscured by the dominant ones in the F1
Gray seed color in peas is dominant to white. Assume that Mendel conducted a series of experiments where plants with gray seeds were crossed among themselves, and the following progeny were produced: 302 gray and 98 white.
(a) What is the most probable genotype of each parent?
(b) Based on your answer in (a) above, what genotypic and phenotypic ratios are expected in these progeny? (Assume the following symbols: G = gray and g = white.)
Gg × Gg; (b) genotypic = 1:2:1, phenotypic = 3:1
Black fur in mice (B) is dominant to brown fur (b). Short tails (T) are dominant to long tails (t). What fraction of the progeny of crosses BbTt × BBtt will be expected to have black fur and long tails?
1/2
In a DNA double helix an adenine of one strand always pairs with a(n) _____ of the complementary strand, and a guanine of one strand always pairs with a(n) _____ of the complementary strand.
thymine; cytosine
After allowing phages grown with bacteria in a medium that contained 32P and 35S, Hershey and Chase used a centrifuge to separate the phage ghosts from the infected cell. They then examined the infected cells and found that they contained _____, which demonstrated that _____ is the phage’s genetic material.
labeled DNA; DNA
Griffith’s experiments with S. pneumoniae were significant because they showed that traits could be transferred from one organism to another. What else did he find that was significant?
The transferred traits were heritable.
In the polymerization of DNA, a phosphodiester bond is formed between a phosphate group of the nucleotide being added and _____ of the last nucleotide in the polymer.
3’ OH
DNA replication is said to be semiconservative. What does this mean?
Each new double helix consists of one old and one new strand.
The first step in the replication of DNA is catalyzed by _____.
Helicase
Short segments of newly synthesized DNA are joined into a continuous strand by _____.
Ligase
In E. coli, which enzyme catalyzes the elongation of a new DNA strand in the 5’ → 3’ direction? At a specific area of a chromosome, the sequence of nucleotides below is present where the chain opens to form a replication fork:
3’ C C T A G G C T G C A A T C C 5’
An RNA primer is formed starting at the underlined T (T) of the template. Which of the following represents the primer sequence?
5’ A C G U U A G G 3’
The leading and the lagging strands differ in that _____.
the leading strand is synthesized in the same direction as the movement of the replication fork, and the lagging strand is synthesized in the opposite direction
In the early to mid-1900s, there was considerable debate about whether protein or DNA was the hereditary material. For what reasons did many researchers assume that protein was the genetic material?
a. There are 20 amino acids that can be used to make up a polypeptide vs the 4 nucleotides that make up a strand of DNA.
b. The structure of proteins is much more complex (size can vary from very small to very large, folded in complicated manners, tertiary and quaternary structure) vs DNA which is just a strand of repeating units of 4 different nucleotides.
c. Proteins have a variety of known functions and at the time DNA had no known function.
What happened when Griffith injected the mouse with the S strain?
Mouse died
What happened when Griffith injected the mouse with the R strain?
Mouse lived
What happened when Griffith injected the mouse with a heat killed S strain?
Mouse lived
What happened when Griffith injected the mouse with a mixture of the heat killed S strain and live R strain?
Mouse died and found living S cells which could reproduce
How did this experiment rule out the possibility that R cells simply used the dead S cells’ capsules to become pathogenic?
The living cells found in the blood sample were able to reproduce to yield more S cells, indicating that the S trait is a permanent, heritable change, rather than a one time use of the dead S cell’s capsules.
What did Griffith conclude from this experiment?
The R strain had been transformed into the S strain by an unknown heritable substance from the dead S cells.
What happened when theprotease treated heat killed S strain was mixed with the live R strain and injected in the mouse?
Mouse died
What happened when the DNase treated heat killed S strain was mixed with the live R strain and injected in the mouse?
Mouse lived
What happened when the RNase treated heat killed S strain was mixed with the live R strain and injected in the mouse?
Mouse died
What type of sugar is present in DNA?
Deoxyribose
What was the conclusion from the Hershey and Chase experiment?
DNA is the genetic material
Why did Meselson and Stahl use radioactive N to label DNA?
Nitrogen atoms are found in the nitrogenous bases of DNA.
What was the overall purpose of Meselson and Stahl’s experiment?
The purpose of the experiment was to determine if DNA replication occurred via the conservative, semi conservative, or dispersive model of DNA replication.
which model of DNA replication was correct in Meselson and Stahl’s experiment?
The semi conservative.
phenotype
observable characteristics
genotype
set of genes that it carries
gene
hereditary unit containing coded info
monohybrid cross
single trait cross
dihybrid cross
two traits cross
autosomal
non-sex chromosomes
What type of macromolecule do most (but not all) genes code for?
proteins
What is a karyotype?
number and visual appearance of the chromosomes in the cell nuclei
True-breeding
offspring of self-pollination
Pleiotrophy
A single gene with multiple phenotypic effects
Epistasis
gene influences expression of another
Law of Segregation:
The two alleles for a heritable character segregate during gamete formation and end up in different gametes
Law of Independent Assortment:
segregation of the alleles are independent from any other one
What is Tay—Sachs disease?
A fatal genetic disorder caused by the build up of a harmful lipid
Who proposed the “Central Dogma”?
Francis Crick
what direction does genetic information flow within a cell?
Genetic information flows from DNA to RNA to Protein.
How many DNA nucleotides code for an amino acid?
3
What is the difference between the template strand and non-template strand of DNA?
The template strand is the strand that will be used to transcribe mRNA from. It is complementary to the mRNA.
Can both strands of DNA serve as template strand?
yes
What are the three phases of transcription?
Initiation, elongation, and termination.
Silent mutation:
a point mutation that has no effect on the amino acid sequence of a protein. Usually occurs in position number 3 of a codon.
Missense mutation:
a point mutation that changes the amino acid sequence of a protein. Will have the greatest effect on protein function if the missense mutation occurs within a critical region of the protein such as an active site or a binding site.
Nonsense mutation:
a point mutation that changes the amino acid codon to a stop codon. This halts the translation of a protein. Nonsense mutations are very detrimental when the mutation halts translation at the very beginning of the mRNA coding segment.
insetion
addition of nucleotide(s) to a gene.
Deletion
loss of nucleotide(s) from a gene
What is a point mutation?
Chemical change in a single base pair of a gene.
who discovered chromosomes had proteins and DNA
Thomas Hunt Morgan
purpose of the pancreas
produces enzymes that digest small carbohydrates, small proteins, polynucleotides, and lipids
purpose of the gallbladder
stores but doesn’t synthesize bile salts
purpose of the oral cavity
mechanical digestion of food
purpose of the SI
produces enzymes that digest disaccharides, small peptides, and nucleotides (NO LIPIDS)
purpose of the LI
absorption of water from alimentary canal
purpose of the stomach
produces pepsin, that has a highly acidic environment
purpose of the esophagus
transports food bolus to the stomach via peristalsis
purpose of the liver
detoxification
purpose of the anus
contains a sphincter that is the terminal part of the body
