Study questions for Bio test #4 Chapters 12,13,14,15
What are genes?
Discrete unit of hereditary information consisting of a specific nucleotide sequence in DNA (or RNA in some viruses)
What are alleles?
Alternative versions of a gene that produce distinguishable phenotypic effects
What is the purpose of mitosis?
Reproduction, growth and development, tissue renewal
What is the purpose of meiosis?
Reduces the number of sets of chromosomes in gametes counterbalancing the doubling that occurs at fertilization
What are the differences between kinetochore microtubules and non-kinetochore microtubules?
Kinetochore microtubules attach to kinetochore and non kinetochores elongate the cell during division
Name the subphases of interphase and describe what occurs during each subphase.
Completes prep for cell division-G2
Name the subphases of mitosis and describe what occurs during each subphase.
Prophase- centrosomes/centrioles and spindle fibers
Prometaphase- kinetochore and nonkinetochore
Metaphase- chromosomes line up at the metaphase plate
Anaphase- sister chromatids separate by shortening of kinetochore microtubules at the kinetochores where motor molecules reside
Telophase- reversal of prophase
What is the restiction point in the cell cycle?
G1 checkpoint where cell receives go ahead to complete G1,S, G2 and M phases and divide and if it doesnt receive go ahead it will exit and switch to non dividing state called G0
What are the hallmarks of each of the subphases of mitosis?
Pro-folding of chromosomes
Prometa-kinetochore and non microtubules
Meta-chromosomes line up at the metaphase plate
Ana-sister chromatids separate by shortening of kinetochore microtubules at the kinetochores where motor molecules reside
Telo-reversal of prophase
What is asexual reproduction?
Generation of offspring from single parent that occurs without fussion of gametes. Offspring are genetically identical to parent.
What is an autosome?
Chromosome that is not directly involved in determining sex; not a sex chromosome
What are sex chromosomes? Give examples.
Chromosome responsible for determining the sex of an individual like X and Y
Who is Gregor Mendel?
Discovered basic principles of heredity by breeding pea plants
Who is Nancy Wexler?
Discovered location of gene that causes huntingtons disease (affects muscle coordination)
Who is T.H. Morgan?
Associated specific genes with specific chromosomes
Who is Mary Lyon?
Discovered X chromosomes can sometimes be inactive
What are the differences between cell plates and cleavage furrows?
Cell plate- double membrane across midline of dividing plant cell between which new cell wall forms during citokinesis
Cleavage furrow- first sign of cleavage in animal cell, a shallow groove in the cell surface near the old metaphase plate
What is the difference between phenotype and genotype?
Phenotype- physical and physiological traits of an organism which are determined by its genetic makeup
Genotype- genetic makeup or set of alleles of an organism
In humans, what is the haploid number of chromosomes?
What human cells are haploid?
Sperm and egg
In humans, what is the diploid number of chromosomes?
What are examples of human diploid cells?
somatic cells- any cell with two chromosome sets
What is an example of an aneuploid number of chromosomes?
Name examples of human disorders due to aneuploidy in autosomes.
Name examples of human disorders due to aneuploidy in sex chromosomes.
Klinefelter syndrome and turner syndrome
Name an example of a human disorder due to a deletion.
cri du chat (cry of the cat)
Name an example of a human disorder that exhibits incomplete dominance.
chronic myelogenous leukemia
Name examples of human disorders that are recessive.
Cystic Fibrosis, Sickle-Cell, tay sachs
Name examples of human disorders that are dominant.
Huntingtons disease, extra toes or fingers, dwarfism
Name examples of human traits [not disorders] that are recessive.
o blood, no freckles, no allergies, blue eyes, small eyes normal hands
Name examples of human traits [not disorders] that are dominant.
freckels, allergies, green eyes, big eyes, webbed toes
What is a Barr body?
Dense object lying along the inside of the nuclear envelope in cells of female mammals representing a highly condensed inactivated x chromosome
Name an example of a phenotype that is due to Barr bodies.
What is a centrosome?
Structure present in the cytoplasm of animal cells important during cell division and functions as a microtubule organizing center and has two centrioles
Where is the centrosome in an animal cell?
What are the differences between chromatin and chromosomes?
Chromatin is the complex of DNA and proteins that makes up a eukaryotic chromosome. When the cell is not dividing chromatin exists in its dispersed form as a mass of very long thin fibers
Chromosomes are cellular structures carrying genetic material found in the nucleus of eukaryotic cells, each one consist of very long DNA molecules and proteins
What is binary fission?
Method of asexual reproduction by division in half. In prokaryotes it does not involve mitosis but in eukaryotes it does
What occurs during prophase l of meiosis that is so important?
How many progeny cells results in one round of mitosis?
Are the progeny cells of mitosis haploid [1n] or diploid [2n]?
How many progeny cells results after meiosis l?
Are the progeny cells of meiosis l haploid [1n] or diploid [2n]?
How many progeny cells results after meiosis ll?
Are the progeny cells of meiosis ll haploid [1n] or diploid [2n]?
Give examples of homozygous dominant genotypes.
Give examples of heterozygous genotypes.
Purple and white flowered offspring
Give examples of homozygous recessive genotypes.
What is hemizygous?
The condition in which genes are present only once in the genotype and not in pairs
What is the metaphase plate?
Imaginary plane midway between the two poles of a cell in metaphase in which the centromeres of all the duplicated chromosomes are located
What are spindle fibers?
Microtubular structures that extend from the centrioles and attach to the centromere of a chromosome during mitosis and meiosis
What is a monohybrid cross?
Heterozygous with respect to a single gene of interest
What is a dihybrid cross?
Heterozygous with respect to two genes of interest
What is a trihybrid cross?
Heterozygous with respect to three genes of interest
What is a test cross?
Breeding an organism of unknown genotype with a homozygous recessive individual to determine the unknown genotype
What are examples of incomplete dominance?
Red snapdragons crossed with white ones
Name an example of co-dominance.
MN blood group
What are the differences between gamete cells and somatic cells?
Gamete- haploid reproductive cell like egg or sperm, unite during sexual reproduction to produce diploid zygote
Somatic- multicellular organism except sperm or egg
What is polyploidy?
Chromosomal alteration in which the organism possesses more than two complete chromosome sets It is result of accident of cell division
What is a polygenic trait? Give examples.
Additive effect of two or more genes on a single phenotypic character like skin color
What are pleiotropic effects? Give a gene that shows pleiotropic effects.
Genes have multiple phenotypic effects like pleiotropic alleles in cystic fibrosis or sickle cell disease
Describe the difference between cross- and self-pollination.
Cross is when a flower can pollinate another and self is when it can pollinate itself
What is the Law of Segregation?
two alleles for a heritable character segregate during gamete formation and end up in different gametes
What is the Law of Independent Assortment of Chromosomes?
Each pair of alleles segregates independently of each other pair of alleles during gamete formation
Name an example of multiple alleles.
ABO blood type
What is epistasis? Name an example of epistasis.
A gene from one locus alters the phenotypic expression of a gene at a second locus. Mouse is homosygous recessive for the second locus the coat is white regardless of black and brown locus
Name the three ways variation of the species occurs due to sexual reproduction.
Independent assortment of chromosomes, random fertilization, crossing over during prophase 1.
What is a karyotype? What does it show us?
Display of chromosome pairs of a cell arranged by size and shape shows there are 2 chromosomes of each 23 types
Describe what the following alterations of chromosomes are: deletion; inversion; reciprocal translocation; and duplication.
Deletion- A deficiency in a chromosome resulting from the loss of a fragment through breakage; A mutational loss of one or more nucleotide pairs from a gene
Inversion- reattachment of a chromosomal fragment in a reverse orientation to the chromosome from which it originated
Reciprocal translocation- attachment of a chromosomal fragment to a nonhomologous chromosome
Duplication- fusion with a fragment from a homologous chromosome such that a portion of chromosome is duplicated
What are sex-linked [aka X-linked] traits?
Due to recessive allele like color blindness
Name examples of sex-linked disorders in humans.
Color blindness, Duchenne muscular dystrophy, Hemophilia
Name a sex-linked trait in the fruit fly.
Body color, wing size
Name examples of sex linked traits that are not disorders in humans.
Eye color, hair color
What are linked genes?
genes located close enough together on a chromosome that they tend to be inherited together
What are cyclins and cyclin dependent protein kinases [Cdks] and how do they provide internal control of cell division?
Cyclin is cellular protein that occurs in a cyclically fluctuating concentration and that plays an important role in regulationg the cell cycle and Cdks is protein kinase that is active only when attached to a particular cyclin look at figure 12.17
What are growth factors and how do they provide external control of cell division?
A protein must be present in the extracellular environment for the growth and normal development of certain types of cells; a local regulator that acts on nearby cells to stimulate cell proliferation and differentiation
What is the difference between transformed cells vs. cancer cells?
What are the differences between the following terms: benign tumor; cancer and metastasis.
Benign is mass of abnormal cells that remain at the site of its origin, cancer cells divide and invade other tissues, mestasis spreads distances away from origin
What is density-dependent inhibition? Do transformed cells have this characteristic?
Crowded cells stop dividing. Transformed cells have this character.
What is anchorage dependency? Do normal cells have this characterisitc?
Requirement that a cell must be attached to a substratum in order to divide. Normal cells have it.
What are homologous chromosomes? Name the three characteristics that defines homologous chromosomes.
Pair of chromosomes of the same length, centromere position, and staining pattern that possess genes for the same characters at corresponding loci. One inherited from father and one from mother.
What are sister chromatids?
Two copies of a duplicated chromosome attaached to eachother by proteins at the centromere and sometimes along arms. Make up one chromosome while joined and chromatids eventally seperate during mitosis or meiosis 2.
Where is the centromere?
Specialized region of the chromosome where two sister chromatids are most closely attached
What are multifactorial traits?
Phenotypic character that is influenced by multiple genes and environmental factors
What is the norm of reaction?
Range of phenotypes produced by a single genotype due to environmental influences
Name the 4 methods of studying the fetus during pregnancy. Which has the least risk to mother and baby?
Ultrasound, aminiocentesis, chorionic villus sampling, fetoscopy. Ultrasound has least risk.
What is genomic imprinting?
Expression of allele in offspring depends on whether the allele is inherited from the male or female parent
What DNA is inherited extranuclearly and maternally?
What is a wildtype organism vs. a mutant?
Wildtype is an indivdual with phenotype most commonly observed in natural populations and mutant is trait that is alternative to wildtype because they are due to alleles assumed to have orginated as changes or mutations in the wildtype allele
Why do humans appear to tolerate extra X and Y chromosomes?