Bio 20A Final/Midterm 3--Guido Bordignon Winter 2023
Who is Gregor Mendel?
- Austrian monk - trained in mathematics and natural history at university of vienna - on his garden plot in the monastery, Mendel noted how characteristics in plants were passed on from one generation to the next
what happens in prometaphase II?
- Nuclear envelope breaks down - Spindles enter the former nuclear area attaching to 2 kinetochores of each chromosome
Describe the process of mitosis
- Start with: Diploid, 2N - Interphase: DNA replication = Dipoid, 4N - Prophase: Condensation of chromatin, appearance of sister chromatids - Metaphase: Sister chromatids align - Anaphase: Sister chromatids separate, centromeres divide - Telophase and Cytokinesis: Two identical, diploid, daughter cells: Diploid, 2N
Which recombination frequency corresponds to independent assortment and the absence of linkage? 0 0.25 0.50 0.75
0.75
what happens during prophase?
1. Chromatin fibers coil up to become discrete chromosomes. 3. Each chromosome consists of two identical sister chromatids, joined at the centromere. 4. Microtubules grow out from the centrosomes, initiating formation of the mitotic spindle.
What happens during prophase II?
1. Chromosomes condense 2. spindles form in each new cell 3. spindle fibers attach to chromosomes. Crossing over does not occur again in Prophase II
what happens during meiosis I?
1. Homologous chromosomes pair to form bivalents. 2. Crossing over (exchange of sections of genetic material) occurs at chiasmata. 3. Cell divides into two. Homologous chromosomes separate randomly. Each cell contains either maternal or paternal copy.
what happens during meiosis II?
1. No replication. 2. Each entering cell has 2 chromatids. 3. Four haploid daughter cells produced.
what happens during metaphase?
1. The mitotic spindle is fully formed 2. The microtubules attached to kinetochores move the chromosomes to the metaphase plate, an imaginary plane equidistant from the poles.
what happens during prometaphase?
1. The nuclear envelope breaks into fragments. 2. Some of the spindle fibers reach the chromosomes and attach to kinetochores, structures made of proteins and specific sections of DNA at the centromeres. 3. Nonkinetochore microtubules overlap with those coming from the opposite pole.
What happens during anaphase?
1. The two centromeres of each chromosome come apart, separating the sister chromatids. 2. The spindle fibers pull apart the chromatids to form two nucleus of the cells.
How do cyclins regulate the cell cycle?
1.Cyclins activate cyclin dependent kinases (CDKs), which control cell cycle processes through phosphorylation. 2.When a cyclin and CDK form a complex, the complex will bind to a target protein and modify it via phosphorylation. 3.The phosphorylated target protein will trigger some specific event within the cell cycle (e.g. centrosome duplication, etc.). 4.After the event has occurred, the cyclin is degraded and the CDK is rendered inactive again. (Cells cannot progress to the next stage of the cell cycle unless the specific cyclin reaches it threshold)
In a cross AaBbCcDd x AaBbCcDd, what is the probability that one of the offspring will have the genotype aaBBCCDd? Assume the genes are unlinked.
1/128
Draw a dihybrid cross between two heterozygous individuals that illustrates the principle of incomplete dominance. Be sure to draw a Punnett square and label the genotype and phenotype of all the individuals involved. What are the odds of a dominant-dominant genotype for both traits?
1/16 --> 1/4 x 1/4
Draw a monohybrid cross between two heterozygous individuals that illustrates the principle of dominant and recessive genes. Be sure to draw a Punnett square and label the genotype and phenotype of all the individuals involved. What are the odds of a dominant-recessive genotype?
1/2
Draw a monohybrid cross between two heterozygous individuals that illustrates the principle of incomplete dominance. Be sure to draw a Punnett square and label the genotype and phenotype of all the individuals involved. What are the odds of a dominant-dominant genotype?
1/4
You flip a coin three times and it comes up heads each time. A friend flips a coin 3 times and it comes up tails each time. What is the probability that both you and your friend will both come up tails on the next toss
1/4
Draw a dihybrid cross between two heterozygous individuals that illustrates the principle of dominant and recessive genes. Be sure to draw a Punnett square and label the genotype and phenotype of all the individuals involved. What are the odds of a dominant-recessive genotype for both traits?
1/4 --> 1/2 x 1/2
Imagine you are performing a cross involving seed color in garden pea plants. What F1 offspring would you expect if you cross true-breeding parents with green seeds and yellow seeds? Yellow seed color is dominant over green. 100 percent yellow-green seeds 100 percent yellow seeds 50 percent yellow, 50 percent green seeds 25 percent green, 75 percent yellow seeds
100 percent yellow seeds
Which of the following codes describes position 12 on the long arm of chromosome 13? 13p12 13q12 12p13 12q13
13q12
Assuming no gene linkage, in a dihybrid cross of AABB x aabb with AaBb F1 heterozygotes, what is the ratio of the F1 gametes (AB, aB, Ab, ab) that will give rise to the F2 offspring? 1:1:1:1 1:3:3:1 1:2:2:1 4:3:2:1
1:1:1:1
In a mating between two individuals that are heterozygous for a recessive lethal allele that is expressed in utero, what genotypic ratio (homozygous dominant:heterozygous:homozygous recessive) would you expect to observe in the offspring? 1:2:1 3:1:1 1:2:0 0:2:1
1:2:1
What are sister chromatids?
2 identical copies of DNA held together by a centromere
how many chromosomes does an egg have?
22 plus 2 X chromosomes
how many chromosomes does sperm have?
22 plus an X or Y
how many chromosomes do human gametes have?
23 chromosomes
How many pairs of chromosomes do humans have?
23 pairs
How many different offspring genotypes are expected in a trihybrid cross between parents heterozygous for all three traits when the traits behave in a dominant and recessive pattern? How many phenotypes? 64 genotypes; 16 phenotypes 16 genotypes; 64 phenotypes 8 genotypes; 27 phenotypes 27 genotypes; 8 phenotypes
27 genotypes; 8 phenotypes
Given the parents AABBCc x AabbCc, what proportion of the progeny will phenotypically resemble the first parent (assuming the genes involved are on different chromosomes)?
3/4
How many chromosomes do humans have?
46 chromosomes
Consider a cross to investigate the pea pod texture trait, involving constricted or inflated pods. Mendel found that the traits behave according to a dominant/recessive pattern in which inflated pods were dominant. If you performed this cross and obtained 650 inflated-pod plants in the F2 generation, approximately how many constricted-pod plants would you expect to have? 600 165 217 468
468
Black fur in mice (B) is dominant to brown fur (b). Short tails (T) are dominant to long tails (t). Of 32 progeny of the cross BbTt x BbTt, approximately how many will have brown fur and short tails? (assume the genes are not linked)
6
The purple (P) allele of a flower color gene is dominant to the white (p) allele. If two heterozygous plants are crossed, __________ of their progeny will have purple flowers.
75%
What is a cell plate?
A cell plate is a arrangement of vesicles that fuse in the middle of a plant cell.
What is a diploid cell?
A cell which contains the full number of chromosomes in homologous pairs.
What is the lac operon?
A collection of genes that are important in coding for enzymes that metabolize lactose.
what is a cell cycle checkpoint?
A control point in the cell cycle where stop and go-ahead signals can regulate the cycle.
What is CDK and what does it do?
A cyclin dependent kinase. Regulates the cell cycle.
What is binary fission?
A form of asexual reproduction in which the parent divides into two approximately equal parts
what is a pathogenic mutation?
A genetic alteration that increases an individual's susceptibility or predisposition to a certain disease or disorder. When such a variant (or mutation) is inherited, development of symptoms is more likely, but not certain.
What is the trp repressor?
A helix-turn-helix protein that binds to the operator site located adjacent to the trp promoter. When tryptophan is present in the cell, two tryptophan molecules bind to the trp repressor, which changes shape to bind to the trp operator.
What is a negative feedback loop?
A negative feedback loop is a system where the output may signal the system to stop changing.
What is a clevage furrow?
A pinch in the cell when it is about to divide.
What does recessive mean?
A trait is hidden unless the genotype is homozygous recessive such as a tt
A diploid cell in G1 has 5 pairs of homologous chromosomes. If this cell underwent meiosis, how many DNA molecules (i.e.DNA double helices) would be present in each gamete after the completion of meiosis? A. 5 B. 10 C. 20 D. 40 E. none of the above
A. 5
Interphase includes which of the following stages of the cell cycle? Check all that apply A. S B. G2 C. M D. G1
A. S B. G2 D. G1
What would happen when a cell undergoing mitosis is fused with a cell in G1? A. The G1 cell would immediately enter mitosis B. The M cell would immediately enter G1 C. Both cells would enter S phase D. The M cell would enter G1, the G1 cell would enter mitosis E. Both cells would enter interphase
A. The G1 cell would immediately enter mitosis
A male mouse with brown fur is crossed to a female mouse with white fur. All the male progeny have white fur while all the female progeny have brown fur. What is the most likely explanation for these data? Assume that the data are highly reproducible and large numbers of progeny were examined. (Check all the apply) A. The brown allele is dominant B. The brown allele is recessive C. The coat color gene is autosomal D. The coat color gene is X-linked E. The female parent is homozygous for the white allele
A. The brown allele is dominant D. The coat color gene is X-linked E. The female parent is homozygous for the white allele
A human cell containing 22 autosomes and a Y chromosome is __________. A. a sperm B. an egg C. a zygote D. a somatic cell of a male
A. a sperm
Sister chromatids are separated during ___________ (check all that apply) A. anaphase of mitosis B. anaphase of meiosis II C. anaphase of meiosis I D. binary fission
A. anaphase of mitosis B. anaphase of meiosis II
Which of the following kinds of cells divide by binary fission? A. bacteria B. human cells C. plant cells
A. bacteria
At metaphase I, homologous chromosomes are connected only at what structures? A. chiasmata B. recombination nodules C. microtubules D. kinetochores
A. chiasmata
Independent assortment occurs during A. metaphase of meiosis I B. metaphase of meiosis II C. metaphase of mitosis D. anaphase of meiosis I E. anaphase of meiosis II F. anaphase of mitosis
A. metaphase of meiosis I
Which of the following statements are false? A. multicellular organisms are always composed of diploid cells B. meiosis leads to the production of haploid gametes C. the fusion of haploid gametes results in the formation of a diploid cell D. haploid cells can reproduce via mitosis E. none of the above
A. multicellular organisms are always composed of diploid cells
A diploid, multicellular life-cycle stage that gives rise to haploid cells by meiosis is called a ________. A. sporophyte B. gametophyte C. spore D. gamete
A. sporophyte
Which of the statements about homologous chromosomes are true A. they carry the same genes in the same order B. the versions (alleles) of the genes they carry may be different C. homologous chromosomes are separated during anaphase of mitosis D. sister chromosomes are homologous E. they have identical DNA sequences
A. they carry the same genes in the same order B. the versions (alleles) of the genes they carry may be different
What is Tay-Sachs disease caused by?
Accumulation of a fatty ganglioside in the nerve cells in the brain because of a single enzyme deficiency inside lysosomes
How does codominance work?
Alleles effect the phenotype in two separate, distinguishable ways. BOTH alleles are present in the phenotype rather than acting as an intermediate between both parental types.
What is an autosome?
Any chromosome that is not a sex chromosome
how do eukaryotic cells reproduce asexually?
Asexual reproduction in single-celled eukaryotes involves mitosis, i.e., duplication of chromosomes and cytoplasm to produce "twin cells" in the process of cell division
how are autosomal genetic diseases passed down?
Autosomal dominant inheritance occurs when a child receives a normal gene from one parent and a defective gene from the other parent. Autosomal means the genetic mutation can occur on any of the 22 non-sex chromosomes in each of the body's cells.
A cell that does not divide for an extended period is in _______ A. S B. G0 C. G1 D. G2 E. Big Trouble
B. G0
Homologous chromosomes are separated during ___________ A. anaphase of meiosis II B. anaphase of meiosis I C. anaphase of mitosis D. telophase of meiosis II E. prophase of meiosis I
B. anaphase of meiosis I
Fungi typically display which type of life cycle? A. diploid-dominant B. haploid-dominant C. alternation of generations D. asexual
B. haploid-dominant
What structure is most important in forming the tetrads? A. centromere B. synaptonemal complex C. chiasma D. kinetochore
B. synaptonemal complex
A eukaryotic cell in G1 has 10 DNA double helices. If this cell underwent mitosis, how many DNA molecules (i.e. DNA double helices) would be present in the cell during prophase? A. 5 B. 10 C. 20 D. 40 E. none of the above
C. 20
Which of the following is not true in regard to crossover? A. Spindle microtubules guide the transfer of DNA across the synaptonemal complex. B. Non-sister chromatids exchange genetic material. C. Chiasmata are formed. D. Recombination nodules mark the crossover point.
C. Chiasmata are formed.
Meiosis I produces: A. Diploid cells with unreplicated chromosomes B. Diploid cells with replicated chromosomes C. Haploid cells with replicated chromosomes D. Haploid cells with unreplicated chromosomes E. gametes
C. Haploid cells with replicated chromosomes
What phase of mitotic interphase is missing from meiotic interkinesis? A. G0 phase B. G1 phase C. S phase D. G2 phase
C. S phase
The term "chromatid" refers to: A. the complex of proteins that assembles at the centromere during mitosis B. DNA and associated proteins C. a highly condensed chromosome that is visible during mitosis or meiosis D. the ends of a chromosome E. DNA wrapped around an octamer of histone proteins
C. a highly condensed chromosome that is visible during mitosis or meiosis
The segregation of alleles occurs during which of the following? A. anaphase of mitosis B. anaphase of meiosis II C. anaphase of meiosis I D. metaphase of meiosis I E. telophase of meiosis II
C. anaphase of meiosis I
One difference between cancer cells and normal cells is that cancer cells __________. A. are unable to synthesize DNA B. are arrested at the S phase of the cell cycle C. continue to divide even when they are tightly packed together D. cannot function properly because they are affected by density-dependent inhibition
C. continue to divide even when they are tightly packed together
The part of meiosis that is similar to mitosis is ________. A. meiosis I B. anaphase I C. meiosis II D. interkinesis
C. meiosis II
A mutation prevents the destruction of cyclin during the cell cycle. The most likely effect of this mutation would be: A. rapid, unregulated cell division B. cancer C. the cell would not exit mitosis D. all of the above E. none of the above
C. the cell would not exit mitosis
Which of the following could account for incomplete dominance? A. sex-linkage B. linkage C. the product of a gene is present in limited quantities D. polygenic inheritance E. environmental effects
C. the product of a gene is present in limited quantities
how do cell-cycle checkpoints regulate cell division?
Cell cycle checkpoints are surveillance mechanisms that monitor the order, integrity, and fidelity of the major events of the cell cycle. These include growth to the appropriate cell size, the replication and integrity of the chromosomes, and their accurate segregation at mitosis.
What is mitosis?
Cell division that generates new cells for growth and repair. The division of one cell into two genetically identical daughter cells
What is the G1 phase?
Cell growth
What is polygenic inheritance?
Characteristics that are influenced by more than one gene (follows bell curve, example: skin color)
What is metaphase?
Chromosomes line up in the middle of the cell
Consider the following cross: P: AABBCC x aabbcc F1: AaBbCc Genes A, B and C are linked. In the absence of recombination, what gametes can be produced by the F1 progeny? Hint: draw out the chromosomes of the parents and their progeny before answering this question. A. No answer text provided. B. AAA, BBB, CCC, aaa, bbb and ccc C. ABC, abc, ABc, abC, AbC, aBc, aBC and Abc D. ABC and abc E. not enough information to tell
D. ABC and abc
Which type of life cycle has both a haploid and diploid multicellular stage? A. asexual B. diploid-dominant C. haploid-dominant D. alternation of generations
D. alternation of generations
Meiosis II produces A. haploid cells with replicated chromosomes B. diploid cells with unreplicated chromosomes C. diploid cells with replicated chromosomes D. haploid cells with unreplicated chromosomes E. somatic cells
D. haploid cells with unreplicated chromosomes
During mitosis, spindle microtubules attach to the ________ of chromosomes. A. centrosomes B. telomeres C. nucleosomes D. kinetochores E. axonemes
D. kinetochores
What are nucleosomes?
DNA and histone molecules which together form a bead-like structure.
What is prophase?
DNA and proteins condense into lightly coiled chromosomes in a nuclear envelope
What is the S phase?
DNA synthesis
what is regulation of RNA stability?
During DNA replication, the single-stranded DNA binding protein (SSB) wraps single-stranded DNA (ssDNA) with high affinity to protect it from degradation and prevent secondary structure formation.
Cell cycle checkpoints ensure that: A. a cell has grown sufficiently prior to division B. DNA damage is repaired prior to DNA replication C. sister chromatids are properly aligned on the metaphase plate prior to anaphase D. DNA has been replicated prior to division E. All of the above
E. All of the above
Sources of genetic variation for organisms that reproduce sexually include: A. independent assortment of chromosomes B. random fusion of gametes C. recombination D. mutation E. all of the above
E. all of the above
what happens during prophase I?
Each chromosome pairs with its corresponding homologous chromosomes to form a tetrad
What does the trp operon do?
Encodes repressible anabolic enzymes involved in the production of the amino acid tryptophan
What is the trp operon?
Encodes repressible anabolic enzymes involved in the production of the amino acid tryptophan
how does environment affect polygenic inheritance?
Environmental factors such as diet, temperature, oxygen levels, humidity, light cycles, and the presence of mutagens can all impact which of an animal's genes are expressed, which ultimately affects the animal's phenotype
what is an x-linked recessive disorder?
Expressed phenotypically in all males who receive it, and, all females who receive it are unaffected
What are the cell cycle checkpoints?
G1, G2, M
how is gene expression can be regulated in eukaryotic cells?
Gene expression in eukaryotic cells is regulated by repressors as well as by transcriptional activators. Like their prokaryotic counterparts, eukaryotic repressors bind to specific DNA sequences and inhibit transcription.
where does genetic regulation occur in a cell?
Gene regulation can occur at any point during gene expression, but most commonly occurs at the level of transcription (when the information in a gene's DNA is passed to mRNA). Signals from the environment or from other cells activate proteins called transcription factors
what are some advantages of gene regulation?
Gene regulation is an important part of normal development. Genes are turned on and off in different patterns during development to make a brain cell look and act different from a liver cell or a muscle cell, for example. Gene regulation also allows cells to react quickly to changes in their environments.
how is genetic testing used by counselors in a clinical setting?
Genetic testing is used for screening, diagnosis, and prognosis of diseases consistent with a genetic cause and to guide drug therapy to improve drug efficacy and avoid adverse effects (pharmacogenomics)
What is the G0 phase?
If the cell does not receive the go ahead for G1, it goes to G0 where it does not replicate.
how does E. coli regulate levels of the enzymes involved in tryptophan biosynthesis?
In E. coli, tryptophan activates a repressor that binds to the trp promoter- operator, inhibiting transcription initiation. In B. subtilis, tryptophan activates an RNA-binding protein, TRAP, which binds to the trp operon leader RNA, causing transcription termination.
How does codominance differ from incomplete dominance?
In codominance, both alleles in the genotype are seen in the phenotype. In incomplete dominance, a mixture of the alleles in the genotype is seen in the phenotype.
What are the differences between asexual and sexual reproduction?
In sexual reproduction, an organism combines the genetic information from each of its parents and is genetically unique. In asexual reproduction, one parent copies itself to form a genetically identical offspring.
How does independent assortment contribute to genetic variation?
Independent assortment produces new combinations of alleles. In meiosis I, crossing over during prophase and independent assortment during anaphase creates sets of chromosomes with new combinations of alleles. Genetic variation is also introduced by random fertilization of the gametes produced by meiosis.
What is interkinesis?
Interphase after Meiosis 1 and before Meiosis 2 during which chromatin uncoils
Describe the process of meiosis
Interphase- Cell growth and synthesis of DNA. Meiosis I Prophase I- Each replicated chromosome pairs with its corresponding homologous chromosome. Metaphase I- paired homologous chromosomes line up across the center of the cell. Anaphase I- Spindle fibers pull up each homologous chromosome pair towrad the opposite end of the cell. Telophase I- a nuclear membrane forms around each cluster of chromosomes. Cytokinesis- forms two new cells. Meiosis II Prophase II- chromasomes-each containing two chromatids- becomes visible. Metaphase II, Anaphase II, and Telophase two are all the same as in Meiosis I the product is just four Haploid cells.
What is pedigree analysis?
Investigation of the occurance of the disease in families to determine type of disease mutation
What is cystic fibrosis?
It is a genetic disorder of the cell membranes. Causes thick, sticky mucus to build up in air passages and pancreas.
What is sickle cell disease?
It is an inherited blood disorder that causes the change in the primary structure of the hemoglobin, and it makes the cells look like sickles.
The genotype XXY corresponds to Klinefelter syndrome Turner syndrome Triplo-X Jacob syndrome
Klinefelter syndrome
what is a M-promoting factor?
Maturation or M phase-promoting factor (MPF) is the universal inducer of M phase common to eukaryotic cells. MPF was originally defined as a transferable activity that can induce the G2/M phase transition in recipient cells.
What is cystic fibrosis caused by?
Mutation in CFTR gene
What is prometaphase?
Nuclear envelope breaks down. Microtubules contact chromosomes at kinetochores.
what is a recombinant chromosome?
One that has been modified by the recombination of parental alleles during crossing over
what is tetrad independent assortment?
Pairs of homologous chromosomes (tetrads) are lined up independently of each other (maternal and paternal chromosomes are also lined up on the metaphase plate at random).
what is a parental chromosome?
Parental chromosomes are the chromosomes found in an offspring that are similar to their parents'. They show the same phenotype as their parents. During meiosis, homologous chromosomes (similar chromosomes from both the parents) join together at a point called chiasmata.
How does incomplete dominance work?
Pattern that occurs when the heterozygote has a phenotype intermediate to the phenotypes of the homozygotes, as when a cross between red-flowered and white-flowered plants produces pink-flowered offspring - it is NOT a mix of the colors! Rather, there is not enough proteins to produce the full red color
what is true breeding
Plants that produce offspring of the same variety when they self-pollinate.
what is post-transcription regulation?
Post-transcriptional regulation is the control of gene expression at the RNA level. It occurs once the RNA polymerase has been attached to the gene's promoter and is synthesizing the nucleotide sequence.
how is gene expression regulated in prokaryotic cells?
Prokaryotic cells can only regulate gene expression by controlling the amount of transcription. As eukaryotic cells evolved, the complexity of the control of gene expression increased. For example, with the evolution of eukaryotic cells came compartmentalization of important cellular components and cellular processes.
The binding of ________ is required for transcription to start. a protein DNA polymerase RNA polymerase a transcription factor
RNA polymerase
what is regulation of RNA processing?
RNA processing is regulated by trans-acting factors such as splicing factors, RNA-binding proteins and cis-sequences in pre-mRNA, and increasing evidence suggests that epigenetic mechanisms, which are important for the dynamic regulation and state of specific chromatic regions, are also involved in co-transcriptional
how does recombination contribute to genetic variation?
Recombination effectively 'shuffles' maternal and paternal DNA, creating new combinations of variants in the daughter germ-cells. Figure 2 Recombination contributes to human genetic variation by shuffling parental DNA and creating new combinations of variants.
what is the difference between recombination and independent assortment?
Recombination occurs during meiosis to create variation, wherein some genes, that are far from each other on a chromosome, can get exchanged( with respect to alleles) while segregating( meiosis I). This does not follow Mendelian inheritance and we get the parental type offsprings as well as recombinants.
how are sex linked genetic diseases passed down?
Sex-linked diseases are passed down through families through one of the X or Y chromosomes. X and Y are sex chromosomes. Dominant inheritance occurs when an abnormal gene from one parent causes disease, even though the matching gene from the other parent is normal. The abnormal gene dominates.
how does heredity influence you chance to get cancer?
Some faulty genes that increase the risk of cancer can be passed on from parent to child. These are inherited cancer gene faults. They occur when there is a fault in the genes in an egg or sperm cell at the time of conception. These faults in the initial sperm or egg cell are copied into every single cell in the body.
What is anaphase?
Spindle fibers pull each chromatid to opposite sides
What is Tay-Sachs disease?
Tay-Sachs disease is an autosomal recessive genetic disease that causes nervous system breakdown and death.
What is linkage?
The case where 2 genes are close together on the same chromosome, such that they do not assort independently in meiosis.
how does E. coli use it's lac operon to digest lactose?
The lac operon of E. coli contains genes involved in lactose metabolism. It's expressed only when lactose is present and glucose is absent. Two regulators turn the operon "on" and "off" in response to lactose and glucose levels: the lac repressor and catabolite activator protein (CAP).
What does polycistronic mean?
The operon has several protein-coding regions that are translated separately.
What is the G2 phase?
The period of the interphase where the cell produces proteins and organelles for the cell division.
how is protein stability regulated?
The primary PTM involved int the regulation of protein stability is ubiquitination, which operates through the ubiquitin-proteasomal system (UPS).
What is asexual reproduction?
The production of genetically identical offspring from a single parent
What is hemizygosity?
The state of having unpaired genes in an otherwise diploid cell; men are normally hemizygous for the genes on the X-chromosome. Hemizygous: Hemi = Half
What does dominant mean?
The trait is visible whenever a dominant allele is present in the genotype such as TT or Tt(both tall)
what are the possible outcomes of genetic testing?
There are three possible results you can receive from genetic testing: positive, negative or uncertain. The meaning of these results depends on multiple factors, such as the type of genetic testing that was performed and your personal and family history, among others.
what is an autosomal dominant disorder?
There must be only one mutated/faulty allele (M) for a certain gene for the disorder to be present
what is an autosomal recessive disorder?
There must be two mutated/faulty alleles (mm) for a certain gene for the disorder to be present
what are Mendel's early theories of heredity?
These simple changes to the phenotype, or the trait displayed in an organism, can be explained through changes in our genes. Mendel's laws include the Law of Dominance and Uniformity, the Law of Segregation, and the Law of Independent Assortment.
How do CDKs promote cell division?
They phosphorylate proteins that allow passage through cell cycle checkpoints.
What happens during cytokinesis in eukaryotes?
This is the step in the cell cycle when the cytoplasm divides in two.
What is in the lac operon in E. coli?
Three lactose genes
what does homologus mean?
To have the same typical structure and position.
what does non-homologus mean?
To not have the same typical structure and position.
what is translational regulation?
Translational regulation refers to the control of the levels of protein synthesized from its mRNA. This regulation is vastly important to the cellular response to stressors, growth cues, and differentiation.
What is telophase?
Two new nuclei form Chromosomes appear as chromatin (threads rather than rods) Mitosis ends
What happens during interphase?
Typically, this phase accounts for 90% of the cell cycle. It is a time of high metabolic activity. The cell grows by producing proteins and organelles, and chromosomes are replicated.
What is ubiquitination?
Ubiquitination is the process of marking a protein for degradation.
what are the levels of chromatin packaging?
We can define three levels of chromatin organization in general terms: DNA wrapped around histone proteins (nucleosomes) like "beads on a string". Multiple nucleosomes coiled (condensed) into 30 nm fiber (solenoid) structures. Higher-order packing of the 30 nm fiber into the eventual familiar metaphase chromosome.
What is post-translational modification?
When certain proteins need additional changes inorder to be functional, like being folded or transported
how do eukaryotic cells regulate the use of lactose?
When lactose is present, an end product of lactose metabolism binds to the repressor protein and prevents it from binding to the operator. This allows RNA polymerase to bind to the promoter and freely transcribe the three genes, allowing the organism to metabolize the lactose.
Abnormalities in the number of X chromosomes tends to have milder phenotypic effects than the same abnormalities in autosomes because of ________. deletions nonhomologous recombination synapsis X inactivation
X inactivation
What is a germ cell?
a cell containing half the number of chromosomes of a somatic cell and able to unite with one from the opposite sex to form a new individual; a gamete.
What happens during cytokinesis in plant cells?
a cell plate forms, followed by a new cell membrane, and finally a new cell wall forms
What is a haploid cell?
a cell that contains one set of chromosomes
what is a haploid cell?
a cell that contains one set of chromosomes
What is progeny?
a descendant or the descendants of a person, animal, or plant; offspring
what is a punnet square?
a diagram that is used to predict an outcome of a particular cross or breeding experiment
what is an unlinked gene?
a gene that far enough away (or on different chromosomes) from another gene that they tend to be inherited independently
What is a clone?
a genetically identical copy of a gene or organism
What is a gamete?
a mature haploid male or female germ cell that is able to unite with another of the opposite sex in sexual reproduction to form a zygote.
What is the trp operon regulated by?
a repressor protein encoded by trpR gene
what is the nucleolus?
a small dense spherical structure in the nucleus of a cell during interphase. makes ribosomes.
What is the mitotic spindle?
a structure made of microtubules that controls chromosome movement during mitosis
What is a test cross and what is it used for?
a test cross is a device that can be used to infer the Mendelian alleles present in parental gametes based on the observation of offspring phenotypes. Specifically, the ratio of phenotypes in a set of offspring reveals missing information about one of the parent's genotypes.
what is a chromosome?
a threadlike structure of nucleic acids and protein found in the nucleus of most living cells, carrying genetic information in the form of genes.
What is the haplotonic life cycle?
a type of life cycle with a dominant haploid stage. Haplontic is a kind of life cycle in Biology where the zygote takes the lead, meaning, zygotes are the only diploid cell. It divides itself mitotically in order to give rise to a brand new plant.
What is an operon?
a unit made up of linked genes that is thought to regulate other genes responsible for protein synthesis.
what is polygenetic inheritance?
additive effect of two or more genes on a single phenotypic character
Which of the following are involved in post-transcriptional control? control of RNA splicing control of RNA shuttling control of RNA stability all of the above
all of the above
Which of the following are true of epigenetic changes? allow DNA to be transcribed move histones to open or close a chromosomal region are temporary all of the above
all of the above
What is recombination?
also called genetic recombination, is the process that introduces genetic diversity into the gametes during meiosis. There are 2 processes that make up recombination: independent assortment and crossing over.
What is the metaphase plate?
an imaginary structure at the midway point between the spindle's two poles
Mendel performed hybridizations by transferring pollen from the _______ of the male plant to the female ova. anther pistil stigma seed
anther
What is a somatic cell?
any cell of a living organism other than the reproductive cells.
What are histones?
any of a group of basic proteins found in chromatin.
how do prokaryotic cells divide using binary fission?
asexual reproduction
Prokaryotic cells lack a nucleus. Therefore, the genes in prokaryotic cells are: all expressed, all of the time transcribed and translated almost simultaneously transcriptionally controlled because translation begins before transcription ends b and c are both true
b and c are both true
how do prokaryotic cells reproduce asexually?
binary fission
By definition, a pericentric inversion includes the ________. centromere chiasma telomere synapse
centromere
How does sex-linked inheritance work?
certain recessive disorders are linked to genes on the sex chromosomes, males and females are affected differently
What is a pedigree?
chart that shows relationships within a family and infers the genotypes of family members
The first suggestion that chromosomes may physically exchange segments came from the microscopic identification of ________. synapsis sister chromatids chiasmata alleles
chiasmata
how do chromatin protect eukaryotic genomes?
chromatin compaction protects DNA from attack by chemical agents.
what happens in metaphase II?
chromosomes line up on metaphase plate
give an example of a sex-linked trait
color blindness and hemophilia
what is the particulate theory of heredity?
discrete "particles" are passed from parents to offspring
Binding of an RNA binding protein will ________ the stability of the RNA molecule. increase decrease neither increase nor decrease either increase or decrease
either increase or decrease
Control of gene expression in eukaryotic cells occurs at which level(s)? only the transcriptional level epigenetic and transcriptional levels epigenetic, transcriptional, and translational levels epigenetic, transcriptional, post-transcriptional, translational, and post-translational levels
epigenetic, transcriptional, post-transcriptional, translational, and post-translational levels
how are alleles, genes, and chromosomes related?
genes and alleles are at the same location on the same chromosome
What is independent assortment?
genes for different traits can segregate independently during the formation of gametes
What is the principle of independent assortment?
genes for different traits can segregate independently during the formation of gametes
How does linkage affect inheritance?
genes located close together on same chromosome DO NOT FOLLOW law of independent assortment-- linked genes can produce new genetic variation possibilities
What is a linked gene?
genes located close together on the same chromosome that tend to be inherited together
What is a genotype?
genetic makeup of an organism
What is lactose?
glucose + galactose
Are eggs and sperm haploid or diploid?
haploid
How does heredity influence your health?
health conditions/disorders can be BIOLOGICALLY passed down from your parents- determines your medical history
What happens in anaphase I?
homologous chromosomes separate and are pulled toward opposite poles
A recessive trait will be observed in individuals that are ________ for that trait. heterozygous homozygous or heterozygous homozygous diploid
homozygous
give an example of epistasis?
in labrador retreievers, black coat is dominant to brown
X-linked recessive traits in humans (or in Drosophila) are observed ________. in more males than females in more females than males in males and females equally in different distributions depending on the trait
in more males than females
If black and white true-breeding mice are mated and the result is all gray offspring, what inheritance pattern would this be indicative of? dominance codominance multiple alleles incomplete dominance
incomplete dominance
What will result from the binding of a transcription factor to an enhancer region? decreased transcription of an adjacent gene increased transcription of a distant gene alteration of the translation of an adjacent gene initiation of the recruitment of RNA polymerase
increased transcription of a distant gene
What is continuous variation?
inheritance pattern in which a character shows a range of trait values with small gradations rather than large gaps between them
what does dominant lethal mean?
inheritance pattern in which an allele is lethal both in the homozygote and the heterozygote; this allele can only be transmitted if the lethality phenotype occurs after reproductive age
what does recessive lethal mean?
inheritance pattern in which an allele is only lethal in the homozygous form; the heterozygote may be normal or have some altered, non-lethal phenotype
What is discontinuous variation?
inheritance pattern in which traits are distinct and are transmitted independently of one another
what are the steps of mitosis?
interphase, prophase, metaphase, anaphase, telophase, cytokinesis
In agriculture, polyploid crops (like coffee, strawberries, or bananas) tend to produce ________. more uniformity more variety larger yields smaller yields
larger yields
how does recombination affect inheritance?
linked genes are usually inherited together because they are carried on the same chromosome. The only thing that can "separate" linked genes and prevent them from being inherited together is genetic recombination — if a crossover occurs between the two genes, they will not be inherited together.
Assume a pericentric inversion occurred in one of two homologs prior to meiosis. The other homolog remains normal. During meiosis, what structure—if any—would these homologs assume in order to pair accurately along their lengths? V formation cruciform loop pairing would not be possible
loop
What is alternative splicing?
mRNA processing events that lead to different combinations of exons being spliced together
The ABO blood groups in humans are expressed as the IA, IB, and i alleles. The IA allele encodes the A blood group antigen, IB encodes B, and i encodes O. Both A and B are dominant to O. If a heterozygous blood type A parent (IAi) and a heterozygous blood type B parent (IBi) mate, one quarter of their offspring will have AB blood type (IAIB) in which both antigens are expressed equally. Therefore, ABO blood groups are an example of: multiple alleles and incomplete dominance codominance and incomplete dominance incomplete dominance only multiple alleles and codominance
multiple alleles and codominance
What happens in telophase II?
nuclear envelope forms around each set of chromosomes
What is a positive feedback loop?
once it is stimulated, it just keeps going (think oxytocin to induce labor)
Cancer causing genes are called ________. transformation genes tumor suppressor genes oncogenes mutated genes
oncogenes
what is a chromatid?
one half of a duplicated chromosome
what is an allele?
one of two or more alternative forms of a gene that arise by mutation and are found at the same place on a chromosome.
what is a reciprocal cross?
paired cross in which the respective traits of the male and female in one cross become the respective traits of the female and male in the other cross
what is blended inheritance?
parental traits become mixed and permanently changed in the offspring
Targeted therapies are used in patients with a set gene expression pattern. A targeted therapy that prevents the activation of the estrogen receptor in breast cancer would be beneficial to which type of patient? patients who express the EGFR receptor in normal cells patients with a mutation that inactivates the estrogen receptor patients with lots of the estrogen receptor expressed in their tumor patients that have no estrogen receptor expressed in their tumor
patients who express the EGFR receptor in normal cells
What is interphase?
period of the cell cycle between cell divisions
The observable traits expressed by an organism are described as its ________. phenotype genotype alleles zygote
phenotype
What is a phenotype?
physical characteristics of an organism
what is the multiplication rule?
probability that 2 or more independent events will occur together is the product of their individual probabilities
The forked line and probability methods make use of what probability rule? test cross product rule monohybrid rule sum rule
product rule
Where does crossing over occur?
prophase 1 of meiosis
where does synapsis occur?
prophase I of meiosis
Post-translational modifications of proteins can affect which of the following? protein function transcriptional regulation chromatin modification all of the above
protein function
Post-translational control refers to: regulation of gene expression after transcription regulation of gene expression after translation control of epigenetic activation period between transcription and translation
regulation of gene expression after translation
If glucose is absent, but so is lactose, the lac operon will be ________. activated repressed activated, but only partially mutated
repressed
what is a contractile ring?
ring of actin and myosin II filaments built at the equator of a cell at the end of mitosis and causes furrowing during cytokinesis
What does homozygous mean?
same alleles
Which is one of the seven characteristics that Mendel observed in pea plants? flower size seed texture leaf shape stem color
seed texture
What is the cell cycle?
series of events that cells go through as they grow and divide
What happens in prometaphase I?
sister chromatids become attached to the kinetochore (strandy part of the spindle), which are attached to the centrsome, part where nuclear envelope breaks
What happens in anaphase II?
sister chromatids separate and move to opposite poles
what are the human gametes?
sperm and egg cells
what is the difference between synaptonemal complex and chiasmata?
synapsis with synaptonemal complex occurs between 2 homologous chromosomes in a tetrad whereas chiasmata with crossing over occurs between 2 homologous chromosomes of another tetrad. this all happens in prophase 1. A is synaptonemal complex and B is chiasmata.
what happens in metaphase I?
tetrads line up at metaphase plate
what is transcriptional regulation?
the activation of specific transcription factors. These can be activators or repressors.
What are epigenetic modifications? the addition of reversible changes to histone proteins and DNA the removal of nucleosomes from the DNA the addition of more nucleosomes to the DNA mutation of the DNA sequence
the addition of reversible changes to histone proteins and DNA
What is cytokinesis?
the cytoplasmic division of a cell at the end of mitosis or meiosis, bringing about the separation into two daughter cells.
what is a telomere
the ends of linear chromosomes
What is crossing over?
the exchange of genes between homologous chromosomes, resulting in a mixture of parental characteristics in offspring.
What is epistasis?
the interaction of genes that are not alleles, in particular the suppression of the effect of one such gene by another.
What is the diplotonic life cycle?
the life cycle of organisms, which is dominated by the diploid stage. Plants and algae show alternation of generation. All the plants showing sexual reproduction alternate between two multicellular stages, viz. Haploid gametophyte and diploid sporophytes.
What is chromatin?
the material of which the chromosomes of organisms other than bacteria (i.e., eukaryotes) are composed. It consists of protein, RNA, and DNA.
What is a Karyotype?
the number and visual appearance of the chromosomes in the cell nuclei of an organism or species.
What is a centromere?
the point on a chromosome by which it is attached to a spindle fiber during cell division.
What is the addition rule of probability?
the probability of any one of several particular events occurring is equal to the sum of their individual probabilities, provided the events are mutually exclusive
What is sickle cell disease caused by??
the substitution of a single amino acid in the hemoglobin protein in red blood cells
what are sequence-specific DNA binding proteins and how do they regulate gene expression?
they regulate the gene expression of different cellular components based on the demands of the cell in response to environmental or physiological signals- ex: trp repressor protein binding/not binding to trp operator for transcription of trp operon to produce trp
What is synapsis in meiosis?
this is known as recombination or crossing over, after sister chromatids recombine they are no longer identical to one another.
what is a the principle of segregation?
two alleles for a gene segregate during gamete formation and are rejoined at random, one from each parent, during fertilization
What does heterozygous mean?
two different alleles
what happens in telophase I?
when the chromosomes have finished moving to opposite ends of the cell.