Unit 2 Homework (Chapters 6, 5, and 7)
In sexually reproducing multicellular organisms, the main functions of mitosis are _____.
- tissue repair/replacement of damaged cells - growth and development
What is a gene?
-A section of DNA that codes for a portion of a protein -A section of DNA that codes for one or more proteins -A discrete sequence of DNA nucleotides
In what way(s) can mRNAs be processed?
-By adding caps and tails to the ends of the mRNAs -By removing the introns (the noncoding regions) of the mRNAs -By splicing the exons (the coding regions) of the mRNAs in different ways
In a dihybrid cross involving two autosomal traits on different chromosomes in which the parentals are purebred for the opposite forms of both traits, how many of the offspring would be expected to be homozygous recessive for both traits?
1 out of 16
Which of the following is evidence for evolution?
1. Bacteria becoming resistant to antibiotics over time 2. Mosquitoes becoming resistant to pesticides 3. Cells with common features and chemically similar DNA
Which of the following mechanisms can drive evolution?
1. Genetic Drift 2. Natural Selection 3. Mutation
What events can lead to offspring having a unique arrangement of their parents' genes?
1. Independent assortment 2. Crossing Over
Assuming complete dominance, what is the expected ratio of genotypes of the offspring following the cross of two heterozygotes?
1:2:1
How many chromosomes did you inherit from your father?
23
If a human diploid cell and a human haploid cell somehow managed to fuse together and not lose any of the chromosomes, how many sets of chromosomes would be inside the newly formed cell?
3
How many nucleotides are required to code for 10 amino acids?
30
A gene is a sequence of DNA nucleotide bases that codes for a single protein. Approximately how many nucleotide bases would be required to code for a protein chain that is 100 amino acids long?
300
The PCR technique doubles the amount of DNA in a sample in each cycle. If you started the PCR technique with two fragments of double-stranded DNA, calculate how many double-stranded DNA fragments you would you have after four cycles.
32
Assuming complete dominance, what is the expected ratio of phenotypes of the offspring following the cross of two heterozygotes?
3:1
How many chromosomes would be found in the karyotype of a Down syndrome female?
47
How many chromosomes would a typical human cell have after mitosis but before cytokinesis?
92
Human white blood cells are often multinucleated (in other words, have more than one nucleus). How many chromosomes would be present in a white blood cell with two nuclei?
92
Which of the following is likely to have the greatest quantity of nectar by volume?
A flower that is orange and horizontal
You plant a flower garden. Which of the following flowers in your garden would be least likely to be pollinated by bees?
A flower that is red and horizontal
What is a "benign" tumor?
A mass of cells that grows out of control but remains at the site of origin
What is a karyotype?
A picture of all the chromosomes in one person's cell
What is recombinant DNA?
A segment of DNA containing sequences from two different sources
A homozygous milk chocolate Easter bunny is crossed with a homozygous dark chocolate Easter bunny. Assuming dark chocolate is dominant over milk chocolate and the traits segregate according to Mendelian genetics, which traits will the offspring express?
All dark
What does "transfer RNA" actually transfer?
Amino acids
The following F1 cross is made: BBGg × Bbgg. Which is not a possible outcome in the F2 generation?
BbGG
A new flower species is discovered in the Amazon. It is blue and upright with concentrated nectar. Which of the following is most likely its pollinator?
Bee
Where does the bond form that binds one strand of DNA to its other strand?
Between the bases
What is the name for the study of the geographic distribution of species?
Biogeography
What type of mutation leads to a frameshift in the reading of DNA?
Both insertions and deletions
If the base sequence of template strand reads GCCATTAC, what is the base sequence of the mRNA?
CGGUAAUG
How is the aging process linked to telomeres?
Cells with short telomeres can no longer divide, so damaged tissues cannot be repaired
DNA plus its associated proteins is called a _______
Chromatin
Which events occur during prophase?
Chromosomes condense and are attached to spindle fibers. The nuclear envelope breaks down.
Why does transcription occur in the nucleus and not in the cytoplasm in eukaryotes?
DNA cannot leave the nucleus
A cloned mammal is made by a similar technique as the one used to produce transgenic animals, except the entire genome is replaced instead of a single gene. This is accomplished by removing the DNA from the unfertilized egg of an egg donor, replacing it with DNA from a normal body cell of a mature animal, and then implanting that cell into the uterus of a surrogate mother. The cell then divides and behaves as if it were a normal embryo. Answer the following question regarding a clone. Of whom is the baby a clone?
DNA donor
Which enzyme is responsible for adding complementary DNA bases to an exposed DNA strand?
DNA polymerase
DNA carries out two basic functions in cells: (1) information storage and transfer (genes can be copied and passed to offspring) and (2) the "blueprint" function (genes provide instructions for building proteins). The key process for information storage and transfer to offspring cells is _____.
DNA replication
The central dogma describes how the genes in the nucleus work to produce an organism's phenotype. Another way of putting it is that the central dogma follows the flow of information from _____.
DNA to protein
What do the letters D-N-A stand for?
Deoxyribonucleic acid
Which grouping includes all of the protists?
Domain Eukarya
When is cell-to-cell communication particularly important in regulating gene expression?
During embryonic development
What is the main cause of cancer?
Exposure to carcinogens in the environment
Some of the "branches" of a phylogenetic tree do not extend to the end. What do these lines represent?
Extinct species
If your grandparents were in the F1 generation, what generation are you in?
F3
Which grouping immediately follows Order in the classification hierarchy?
Family
A cloned mammal is made by removing the DNA from the unfertilized egg of an egg donor, replacing it with DNA from a cell of a mature animal, and then implanting that cell into the uterus of a surrogate mother. The cell then divides and behaves as if it were a regular embryo. Answer the following question(s) regarding a clone. Will the clone typically be sterile or fertile?
Fertile
What type of cells do not undergo mitosis?
Gametes
What separates the strands of DNA in the polymerase chain reaction (PCR) technique?
Heat
Which genes are responsible for your overall structure, such as how many legs you have and where they develop?
Homeotic genes
What specifically separates during meiosis I?
Homologous chromosomes
DNA helicase breaks which type of bond in the DNA molecule?
Hydrogen bonds
Where does translation occur in eukaryotes?
In the cytoplasm only
What defines a population in evolution?
Interbreeding members of the same species
During which phase of the cell cycle are the chromosomes duplicated?
Interphase
How does a scientist get the corrected version of a gene into the cells of a gene therapy patient?
It is delivered with a modified virus.
When I say a flower is "purple," what have I described?
Its phenotype
What is the name of the syndrome that produces the XXY combination of sex chromosomes?
Klinefelter syndrome
What describes melanin's function?
Lighter skin has less of the dark-brown eumelanin that protects cells from UV damage
Is an individual with the XXY combination of chromosomes anatomically male or female?
Male
What produces four daughter cells?
Meiosis
What produces genetically unique daughter cells?
Meiosis
When does crossing over occur?
Meiosis I
A zygote (i.e., a fertilized egg) undergoes development to grow. What mechanism is used to generate more cells?
Mitosis
Which process requires DNA to undergo duplication before it can proceed?
Mitosis and Meiosis
Can you inherit physical traits that your parents acquired during their lifetime?
No
Is most of our DNA made up of genes?
No, genes make up only 1.5% of our DNA.
Do all cells of the body express the same genes?
No, since they don't all need to make the same proteins
Can the PCR technique be used to copy an entire chromosome all at once?
No, the PCR machine can only copy fragments of DNA
Is the number of chromosomes in each cell of an organism a good indicator of the complexity of that organism?
No, the number of chromosomes does not indicate how complex an organism is
What leads to an individual having too many or two few chromosomes?
Nondisjunction
Which of the following is the correct sequence of events during mitosis?
Nuclear membrane dissolves, chromosomes line up, chromosomes split, nuclear membrane forms
How have Mendel's laws fared as we have learned more about cell biology and processes such as meiosis?
Our new knowledge has helped to explain some of the exceptions to Mendel's laws of inheritance
Which two observations led Darwin to conclude that there is competition for survival?
Overproduction and limited resources
Assuming incomplete dominance, if a homozygous red-flowered plant is crossed with a homozygous white-flowered plant, what will be the color of the offspring?
Pink
Which of the following is not a modification to the mRNA?
Promoter binding
How does a cell typically know when to divide?
Proto-oncogenes code for growth factor proteins that initiate cell division
If DNA directs the production of RNA, what does RNA make?
RNA makes proteins
Which of the following processes does not generate genetic variation during sexual reproduction?
Random fertilization Independent assortment Crossing over They all are process that generate genetic variation
What is the name of the enzyme that builds cDNA out of mRNA?
Reverse transcriptase
What are attached at the centromere?
Sister chromatids
What specifically separates during meiosis II?
Sister chromatids
According to the base pairing rules of DNA, if the sequence of bases on one strand was AGGCTTA, what would be the sequence of bases on the complementary strand?
TCCGAAT
Prior to the publication of Charles Darwin's book, On the Origin of Species, what was the prevailing public consensus regarding species evolution?
That species were permanent and unchanging
What is different from one DNA nucleotide to the next?
The base
What does it mean when we say a gene is "turned off"?
The gene cannot be transcribed and translated into a protein
Why can a person who is unable to produce insulin be successfully treated with insulin derived from genetically modified bacteria?
The gene that produces insulin in humans was inserted into the bacteria where it continues to produce human insulin
What is different between two alleles of the same gene?
The information they carry. For example, one allele might carry the information for blue eye pigment, while the other carries the information for brown eye pigment.
Define Mendel's law of independent assortment
The inheritance of one character has no effect on the inheritance of another character
What is the smallest unit that can evolve?
The population
Three of the following statements are correct. Identify the statement that is not correct regarding genetically modified organisms.
There are no risk associated with GM crops
What is the role of primers in the PCR techniques?
To target specific areas of DNA
Which process results in the creation of mRNA?
Transcription
How is translation initiated?
Two ribosomal subunits bind to the mRNA transcript
If the codon is AAA, what is the complementary anticodon?
UUU
What is the main function of DNA helicase in DNA replication?
Unzipping the DNA double helix
When might a frameshift or nonsense mutation not result in a completely defective protein?
When the mutation occurs in one of the very last codons
Barr bodies are associated with ________.
X chromosome inactivation
Can one gene make different proteins?
Yes, by splicing the resulting mRNA differently (i.e., removing different exons)
Are there ways to prevent cancer?
Yes, there are many ways cancer can be prevented, including through a healthy diet and exercise
Some may be obvious, like people with red hair or double jointed thumbs. This loss of diversity in a reduced population is called ________.
bottleneck effect
Two alleles of the same gene ________
can be the same or can be different
Evolution can be best defined as ________.
change in allele frequency in a population
Genes are located on ________.
chromosomes
Somatic cells are ________.
diploid (2n)
Meiosis starts with _____ cells and produces _____ gametes.
diploid, haploid
Cytokinesis _____.
finishes mitosis by dividing the cytoplasm and organelles of the original parent cell into two separate daughter cells
A page is to a book as a ___________ is to the genome.
gene
Which of the following is the largest unit of DNA organization?
genome
A collection of cloned DNA fragments representing the organism's entire genome is called a ________.
genomic library
Fertilization joins _____ to produce a _____.
haploid gametes, diploid zygote
A test cross is performed to determine if a specific individual is a carrier. The results generate a 50/50 ratio of phenotypes. The test subject is therefore ________.
heterozygous (Aa)
The _____ separate in meiosis I; the _____ separate in meiosis II.
homologous chromosomes, sister chromatids
Natural selection acts on ________, and ________ evolve.
individuals, populations
A weed that exhibits resistance to an herbicide ________.
inherited the gene that made it resistant to the herbicide
During _____, the cell carries out its normal functions and the chromosomes are thinly spread out throughout the nucleus.
interphase
Gel electrophoresis separates DNA fragments according to their ________.
length
Genes located near one another on the same chromosome are often inherited together. These are called ________.
linked genes
A particular gene does NOT constantly churn out the same protein at all times in every cell. This is true for two reasons. First, _____ can allow one gene to produce several different proteins. Second, genes are constantly being turned on and off through the process of _____.
mRNA processing, gene regulation
Recessive disorders related to genes found on the X chromosome but not on the Y are more commonly expressed in ________.
males
In _____ isolation, it is physically impossible for two species to mate with each other, often because their genitalia do not fit together properly.
mechanical
If it weren't for _____, chromosome number would double with every generation of sexual reproduction.
meiosis
Looking through a light microscope at a cell undergoing meiosis, you see that the chromosomes have joined into XX-shaped tetrads. These tetrads are lined up along a plane that runs through the center of the cell. This cell is in _____.
meiosis I
The homologous pairs are NOT joined in tetrads. Each chromosome takes its own place in line, independentof its homolog. You are witnessing _____.
metaphase of mitosis
The spread of cancer cells from their site of origin to sites distant in the body is called ________.
metastasis
Dead or damaged cells are replaced by the process of ________.
mitosis
A sugar, a phosphate, and a base are the components of a __________.
nucleotide
What is the monomer of the DNA molecule?
nucleotide
Mendel formulated his principles of inheritance based on _____.
observations on the outcomes of breeding experiments. The underlying processes were unknown at the time.
Duplication of the chromosomes to produce sister chromatids _____.
occurs in both mitosis and meiosis
The signal transduction pathway allows ________.
one cell to regulate the gene expression of another cell
The small circular molecules of DNA commonly found in bacteria are called ________.
plasmids
Gene cloning is used to ________.
produce large quantities of human proteins
All prokaryotes are in the domain ________.
prokaryotes are in two different domains
Which nucleic acid acts like an enzyme, stabilizing and orienting different molecules to facilitate the formation of bonds between them?
rRNA
What are telomeres?
regions of DNA at the end of chromosomes which do not code for making proteins
The function(s) of meiosis is/are _____.
reproduction (production of gametes)
Darwin thought that significant evolution was much too slow to be witnessed in a human lifetime. Recent experiments by biologists have _____.
shown that some populations can evolve quite rapidly, with important changes occurring over several generations in the laboratory
The type of mutation that alters the nucleotide sequence of a gene but does not alter the amino acid sequence of the protein produced from that gene is called ________ mutation.
silent
Mitosis occurs in _____; meiosis occurs in _____.
somatic or body cells, germ cells in the testes or ovaries
Which of the following make up the backbone of a polynucleotide strand?
sugar and phosphate
Individuals with variations that make them best suited to their environment will, on average, be more likely to ________.
survive and reproduce
The chromosomes then begin to disappear as they unwind. You arewitnessing _____.
telophase
Eastern and western spotted skunks breed at different times of the year. Therefore, they are prevented from interbreeding by _____ isolation.
temporal
If two organisms of different species share more similar DNA sequences with each other than with other species, we can conclude that ________.
these two species are very closely related
Meiosis is typically accomplished in _____.
three steps. All of the chromosomes are duplicated in a diploid cell, and then there are two cell divisions to produce a total of four haploid gametes.
Genetically modified organisms that acquire genes from a different species are called ________ organisms.
transgenic
tRNA molecules work to _____.
translate mRNA to produce a specific amino acid sequence
How many polynucleotides are found in one molecule of DNA?
two
When one cell goes through cell division, it produces ________.
two identical cells
If genes are described as "sex linked," then they are ________.
typically on the X chromosome
Cancer is ________.
uncontrolled cell growth
The offspring produced via sexual reproduction are genetically ________ to the parents.
unique
DNA profiling relies on an individual's ________, no two of which are the same between different people, except identical twins.
unique set of short tandem repeats within DNA
The genetic code is ________.
what allows codons to be translated into amino acids
Upon fertilization, the egg and sperm fuse to form a single cell called a(n) ________.
zygote