BIOL 1201 Exam 3
snRNPs
"snurps"; small nuclear ribonucleus-proteins
In certain plants, tall is dominant to short. If a heterozygous plant is crossed with a homozygous tall plant, what is the probability that the offspring will be short?
0
When PPYY individuals breeds with ppyy individual, and p and y are unlinked, what proportion of the next generation is ppyy?
0%
Gametes possess how many copies of unique chromosomes?
1
With linked genes M and N, what proportion of the cross MMNN x mmnn will be MmNn (without any crossing over)?
1
3 reasons Mendel worked with peas
1. simple, obvious characters (seed shape and color) 2. different traits for each character(round/wrinkled) 3. no blending occurs
Crossing a GgHhJj individual with a GgHhJj individuals (assuming independent assortment and no crossing over) would yield what proportion of GgHhJJ offspring? A) 1/32
1/16
When PpYY individuals interbreed, and there is independent assortment, what proportion of the next generation is PpYY?
1/2
With sex linkage, what proportion of a female dd crossing with a male Dy will have the D phenotype (dominant)?
1/2
Crossing Rr x Rr yields what proportion of rr offspring?
1/4
Crossing XxYy with XxYy with independent assortment yields what proportion of XxYy offspring?
1/4
When PpYy individuals interbreed, and there is independent assortment, what proportion of the next generation is Ppyy?
1/8
Cinnabar eyes is a sex-linked recessive characteristic in fruit flies. If a female having cinnabar eyes is crossed with a wild-type male, what percentage of the F1 males will have cinnabar eyes?
100%
A group of cells is assayed for DNA content immediately following mitosis and is found to have an average of 8 picograms of DNA per nucleus. How many picograms would be found at the end of S and the end of G2?
16; 16
Initiation
1st part of transcription; RNA polymerase binds to promoter and opens the double helix
A diploid cell has how many copies of unique chromosomes?
2
Elongation
2nd part of transcription; RNA polymerase adds nucleotides to complement the DNA template
A particular triplet of bases in the template strand of DNA is 5' AGT 3'. The corresponding codon for the mRNA transcribed is
3' UCA 5'.
When YyRr individuals interbreed, and there is independent assortment, what proportion of the next generation is green and round?
3/16
What will be the ratio of eye-color in the F2 generation of these flies?
3:1
Termination
3rd part of transcription; RNA polymerase separates from DNA
If humans have 23 unique chromosomes, how many chromosomes does a human liver cell have?
46
The phosphate group is connected to which position on the deoxyribose?
5'
An Okazaki fragment has which of the following arrangements?
5' RNA nucleotides, DNA nucleotides 3'
TATA box
A DNA sequence in eukaryotic promoters crucial in forming the transcription initiation complex
Chromosome
A cellular structure carrying genetic material, found in the nucleus of eukaryotic cells. Each chromosome consists of one very long DNA molecule and associated proteins
Mutation
A change in the nucleotide sequence of an organism's DNA
In mitosis, there are chromosomes and chromatids. What is a chromatid?
A copy of a chromosome
Domain
A discrete structural and functional region of a protein
Gene
A discrete unit of heriditary information consisting of a specific nucleotide sequence in DNA
Polyribosome
A group of several ribosomes attached to, and translating, the same mRNA molecule
Splicesome
A large complex made up of proteins and RNA molecules that splices RNA by interacting with the ends of an RNA intron, releasing the intron and joining the two adjacent exons
DNA Ligase
A linking enzyme essential for DNA replication; catalyzes the covalent bonding of the 3' end of one DNA fragment to the 5' end of another DNA fragment
Introns
A non-coding, intervening sequence within a primary transcript
Anticodon
A nucleotide triplet at one end of a tRNA molecule that base-pairs with a particular complementary codon on an mRNA molecule
The expression of DNA or RNA is controlled by factors. What is a factor?
A protein that attaches to DNA or RNA and helps
Transcription factor
A regulatory protein that binds to DNA and affects transcription of specific genes
Exons
A sequence within a primary transcript that remains in the RNA after RNA processing
What's a general term used by geneticist for a brain or muscle cell?
A somatic cell
Locus
A specific place along the length of a chromosome where a given gene is located
Epistasis
A type gene interaction in which the phenotype expression of one gene alters that of another independently inherited genes
mRNA
A type of RNA, synthesized using a DNA template, that attaches to ribosomes in the cytoplasm and specifies the primary structure of a protein
Mendel's hypothesis of inheritance
ALternative forms of genes, dominant/recessive genes, one gene from each parent, two alleles for each character separate during gamete production
RNA splicing
After RNA synthesis of a eukaryotic primary RNA transcript, the removal of portions of the transcript (introns) that will not be included in the mRNA and the joining together of the remaining portions (exons)
tRNA
An RNA molecule that functions as a translator between nucleic acid and protein languages by carrying specific amino acids to the ribosome, where they recognize the appropriate codons in the mRNA.
DNA Polymerase
An enzyme that catalyzes the elongation of new DNA by the addition of nucleotides to the 3' end and end of an existing chain.
Primase
An enzyme that joins RNA nucleotides to make a primer during DNA replication, using the parental DNA as a template
Helicase
An enzyme that untwists the double helix of DNA at replication forks, separating the two strands and making them available as template strands
Character
An observable heritable feature that may vary among individuals (color)
Allele
Any of the alternative versions of a gene that may produce distinguishable phenotype effects
How are genetic data encoded in DNA?
By the sequence of the nucelotides
tRNA does what?
Carries amino acids to the ribosomes-mRNA complex
Point mutation
Caused by a single nucleotide substitution resulting in an amino acid substitution
When Mendel coded purple flowers and white flowers, what were the characters and traits?
Character= color; Trait= purple or white
During anaphase of mitosis, human cells have 92 chromosome. How can that be?
Chromatids separate and form discrete chromosomes in anaphase
Recombination between linked genes comes about for what reason?
Crossovers between these genes result in chromosomal exchange.
In trying to determine whether DNA or protein is the genetic material, Hershey and Chase made use of which of the following facts?
DNA contains phosphorus, but protein does not.
Transcription occurs in the nucleus?
Depends on the organism
The role of chromosomes in genetic inheritance was realized at the beginning of the 20th Century because of the fusion of what two events.
Development of cytology and discovery of Mendel's work
Which of the following is true of a species that has a chromosome number of 2n = 16?
Each cell has eight homologous pairs.
Heterologous chromosomes carry the same genes? T/F
False
Zygotes are haploid? T/F
False
Mendel's characters and traits are analogous to what?
Genes and alleles, respectively
Which of the following are primarily responsible for cytokinesis in plant cells but not in animal cells?
Golgi-derived vesicles
Heterozygous
Having two different alleles for a given gene
Homozygous
Having two identical alleles for a given gene
Sex determination
Humans: XX- female XY- male Insects: XX-female XO- male Birds/fish: ZW- female ZZ- male Bees/ants: Diploid- female Haploid- male
What kind of bonds hold the two strands of DNA together in the double helix?
Hydrogen
What is removed when pre-RNA is converted to mRNA?
Introns
If a cell has completed the first meiotic division and is just beginning meiosis II, which of the following is an appropriate description of its contents?
It has half the amount of DNA as the cell that began meiosis.
What is the heterogametic sex in humans.
Male
Differences between Mitosis and Meiosis
Mitosis: duplicated chromosomes with sister chromatids, chromosomes align on metaphase plate, two 2n daughter cells Meiosis: tetrads formed (crossing over), tetrads align on metaphase plate, four 1n daughter cells
In his transformation experiments, what did Griffith observe?
Mixing a heat-killed pathogenic strain of bacteria with a living nonpathogenic strain can convert some of the living cells into the pathogenic form.
Independent Assortment
Occurs during metaphase I; homologous chromosomes aligning on different sides of the metaphase plate
Crossing over
Occurs during prophase I; when tetrads are formed, some of the DNA from each chromosome is exchanged
A site
One of a ribosome's three binding sites for tRNA during translation. The A site holds the tRNA carrying the next amino acid to be added to the polypeptide chain
E site
One of a ribosome's three binding sites for tRNA during translation. The E site is the place where discharged tRNAs leave the ribosome
P site
One of a ribosome's three binding sites for tRNA during translation. The P site holds the tRNA carrying the growing polypeptide chain
Trait
One of two or more detectable variants in a genetic character (purple/ white)
Why did the F1 offspring of Mendel's classic pea cross (PP x pp) always look like one of the two parental varieties?
One phenotype was completely dominant over another.
Why does an organism's liver cell have 2 copies of each chromosome?
One set is inherited from the organism's mother, and one from its father
34. When Pp individuals interbreed, what are the genotypes of the gametes?
P and p
What is the first product of transcription in eukaryotes?
Pre-RNA
What is transcription?
Production of RNA and DNA
What is translation?
Production of polypeptides from an mRNA template
Why does the DNA double helix have a uniform diameter?
Purines pair with pyrimidines.
If "P" codes for purple flowers, and "p" codes for white flowers, what is the phenotype of a "Pp"?
Purple
All of these are enzymes employed in DNA replication except?
RNA Polymerase
Which enzyme produces the most transcript in transcription?
RNA Polymerase
Which of the following is true for both prokaryotic and eukaryotic gene expression?
RNA polymerase binds to the promoter region to begin transcription.
In which of the following actions does RNA polymerase differ from DNA polymerase?
RNA polymerase can initiate RNA synthesis, but DNA polymerase requires an RNA primer to initiate DNA synthesis.
Independent assortment refers to?
Random mixing of heterologous chromosomes in meiosis
In this test cross of a fruitfly with a sex-linked white eye mutation, what will the F1 offspring look like?
Red eyed
Mendelian segregation of alleles results from?
Separation of homologous chromosomes in meiosis
Chiasmata
The X shaped, microscopically visible region where crossing over has occurred earlier in Prophase I between homologous non-sister chromatids
Pleiotrophy
The ability of a single gene to have multiple effects
A plant-derived protein known as colchicine can be used to poison cells by blocking the formation of the spindle. Which of the following would result if colchicine is added to a sample of cells in G2?
The chromosomes would coil and shorten but have no spindle to which to attach.
Chromatin
The complex of DNA and proteins that make up eukaryotic chromosomes.
G1 phase
The first growth phase of the cell cycle, consisting of the proportion of interphase before DNA synthesis begins
DNA Replication
The process in which a DNA molecule is copied; also called DNA synthesis
Centromere
The region on each sister chromatid where they are most closely attached to each other by proteins that bind to specific DNA sequences; this close attachment causes a constriction in the condensed chromosome
Genetics
The scientific study of heredity and heredity variation
G2 phase
The second growth phase of the cell cycle, consisting of the proportion of interphase after DNA synthesis occurs
Incomplete dominance
The situation in which the phenotype of heterozygotes is intermediate between the phenotypes of individuals homozygous for each other
Independent assortment of chromosomes occurs
The statement is true for meiosis I only.
Chromatids are separated from each other.
The statement is true for mitosis and meiosis II.
Transcription
The synthesis of RNA using a DNA template
Translation
The synthesis of a polypeptide using genetic info encoded in an mRNA molecule. There is a change of "language" from nucleotides to amino acids.
S phase
The synthesis phase of the cell cycle; the proportion of interphase during which DNA is replicated
Heredity
The transmission of traits from one generation to the next
In a two gene cross (a dihybrid cross), what do offspring frequencies of 50% parentals and 50% recombinants indicate?
The two genes are likely to be located on different chromosomes.
What happens to the gametes after they are produced?
They join with other gametes in reproduction or do nothing
In the double helix of DNA, Adenine is always opposite?
Thymine
What is the purpose of mitosis?
To make daughter cells exactly like the parent cells
What is the purpose of DNA replication?
To make more DNA for cell division
What is the purpose of Meiosis?
To make sex cells
Why is there sex?
To mix up genes (proximate)/ to create different types of individuals in population (ultimate)
Translation occurs in the cytoplasm? T/F
True
sister chromatids
Two copies of a duplicated chromosome attached to each other by proteins at the centromere and sometimes at the arms. While joined, two sister chromatids make up one chromosome. Chromatids are eventually separated during mitosis or meiosis II
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
During which phase of mitosis do the chromatids become chromosomes?
anaphase
Heterologous
different chromosomes carrying different genes
An individual with genotype AaBbCCDdEE can make many kinds of gametes. Which of the following is the major reason?
different possible alignments of chromosomes
Once transcribed, eukaryotic mRNA typically undergoes substantial alteration that includes
excision of introns.
Ribosomes
functions as the site of protein synthesis; has alarge and small subunit
What are polyribosomes?
groups of ribosomes reading a single mRNA simultaneously
Tetrads
homologous chromosomes pair creating tetrads in prophase I
The human X and Y chromosomes
include genes that determine an individual's sex.
Random Fertilization
millions of different combinations of sperm and egg
Hydra
multicellular asexual organism
X inactivation
only one of the X chromosomes in females are active, the other is inactivated during early development
When we see chiasmata under a microscope, that lets us know which of the following has occurred?
prophase I of meiosis
At which phase are centrioles beginning to move apart in animal cells?
prophase-prometaphase
Missense mutation
results in a protein in which one amino acid is substituted for another
Nonsense mutation
results in a stop codon, which causes traslation to stop
It became apparent to Watson and Crick after completion of their model that the DNA molecule could carry a vast amount of hereditary information in which of the following?
sequence of bases
Polygeny
several genes control a single character (skin pigmentation)
Transcription in eukaryotes requires which of the following in addition to RNA polymerase?
several transcription factors
Human cells have autosomes and...
sex chromosomes
The process of translation, whether in prokaryotes or eukaryotes, requires mRNA, amino acids, ribosomal subunits, and which of the following?
tRNA
Prophase 1 in meiosis differs from prophase in mitosis by the existence of...
tetrads
The strands that make up DNA are antiparallel. This means that
the 5' to 3' direction of one strand runs counter to the 5' to 3' direction of the other strand
Chargaff's analysis of the relative base composition of DNA was significant because he was able to show that
the amount of A is always equivalent to T, and C to G.
Which of the following defines a genome?
the complete set of an organism's genes
Homologous
the same kind of chromosome, carrying the same genes
Why do chromosomes coil during mitosis?
to allow the chromosomes to move without becoming entangled and breaking
Particulate theory
traits are inherited as "particles", offspring receive a "particle" from each parent.
Mendel's law of segregation
you get these alleles going to different gametes which occurs in Anaphase I
When Pp individuals interbreed, what proportions of genotypes occur in the next generation?
¼ PP, ½ Pp, ¼ pp
