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BIO 121 Exam 3 Review Questions And
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Binary fission
a method of asexual reproduction; "division in half"; involves mitosis in eukaryotes
Mitosis
a process of nuclear division in eukaryotes
What are the 5 stages of Mitosis?
- Prophase
- Prometaphase
- metaphase
- anaphase
- telophase
Meiosis
A modified type of cell division in sexually reproducing organisms consisting of 2 rounds of cell division, but one round of DNA replication. Half number of chromosome sets as original cell
Sexual Reproduction
A type of reproduction in which two parents give rise to one offspring that have unique combination of genes inherited by both parents via gametes
Asexual Reproduction
A type of reproduction with one parent; no fusion of gametes; budding, division of a single cell; genetically identical to the parent
Haploid
A cell containing one set of chromosomes
Diploid
A cell containing two sets of chromosomes; one from each parent
Prophase
1st stage of mitosis; chromatin (chromosomes) condense
Prometaphase
2nd stage of mitosis; nuclear envelope fragments; each chromatid gets a kinetochore
Tubulin
Globular protein that constructs the wall of the microtubules
Sister Chromatid
2 copies of a duplicated chromosome attached to each other at the centromere (sometimes along arms)
Microtuble
A hallow rod composed of tubulin proteins that make up part of the cytoskeleton in all eukaryotic cells
Centrosome
in cytoplasm of animal cells; functions as a microtubule organizing center
Centromere
the region on each sister chromatid where they are most closely attached to each other ; in a duplicated chromosome
Mitotic spindle
An assemblage of microtubules ; involved in movement of chromosomes
Kinetochere
A structure of proteins attached to the centromere that links each sister chromatid to the mitotic spindle
Homologous Chromosomes
A pair of chromosomes of the same length, centromere position and staining pattern that possesses genes for the same characters at corresponding loci
Separase
An enzyme that starts the anaphase stage of mitosis; separates the sister chromatids
Cyclin
A cellular protein that occurs in a cyclically fluctuating concentration and that plays an important role in regulating the cell cycle
Cyclin dependent kinase (cdk)
A protein kinase that is active only when attached to a particular cyclin
MPF
Maturation - promoting factor; protein complex required for a cell to progress from late interphase to mitosis;helps initiate mitosis
Gametes
characteristics are passed from one generation to the next through discrete particles (genes) that retain their ability to be expressed, even though they may not appear in every generation
Genotype
The genetic makeup or set of alleles of an organism
Phenotype
The observable physical and physiological traits of an organism , determined by the genotype
Parental generation
The true breeding (homozygous) parent individuals from which F1 hybrid offspring are derived
F1 generation
The first initial hybrid (heterozygous) offspring arisi ng from p generation
F2 generation
The offspring resulting from interbreeding of F1 hybrid generation
Dominant
an allele that is fully expressed in the phenotype of a heterozygote
Recessive
allele with no phenotypic effect that is observable in a heterozygote
Homozygous
Having two identical alleles for a given gene
Heterozygous
having two different alleles for a given gene
Indep. Segregation
during gamete formation the segregation of the alleles of one allelic pair is independent of the segregation of the alleles of another allelic pair
As with the monohybrid crosses, Mendel confirmed the results of his second law by performing a backcross - F1 dihybrid x recessive parent.
Indep. Assortment
The fact that the inheritance of (most) genes do not influence each other
Genetic Transformation
is the genetic alteration of a cell by the direct uptake and expression of DNA from its surroundings. Transformation occurs naturally in some species of bacteria, and can also be done artificially; with Plasmids
Phage
A virus that infects bacteria
X-ray diffraction
The scattering of X-rays by the regularly spaced atoms of a crystal, useful in obtaining information about the structure of the crystal; Rosalind Franklin used this to show DNA was composed of two helices (coils)
Anti- Parallel
Refers to the to the arrangement of the sugar-phosphate backbones in a DNA double helix (run in opposite directions 5' to 3')
Double Helix
The form of native DNA, referring to its two adjacent antiparallel polynucleotide strands wound around an imaginary axis into a spiral shape
Complimentary strand of DNA
A double stranded DNA molecule made invitro using mRNA as a template and the enzyme reverse transcriptase and DNA polymerase ; corresponds to the exons of a gene
Template Strand
The DNA strand that provides the pattern, or template , for ordering , by complimentary base pairing , the sequence of nucleotides in an RNA transcript
Chargaff's rules
A purine always pair with a pyrimidine (base pairs); A (Adenine) and T(Thymine), C(Cytosine) and G(Guanine).
Nucleotide
The building block of nucleic acid, consisting of five carbon sugar covalently bonded to a nitrogenous base and one or more phosphate groups
Conservative model of DNA synthesis
The two parental strands reassociate after acting as templates for new strands thus restoring the parental double helix
Semi Conservative model
The two strands of the parental molecule separate and each functions as a template for synthesis of a new complimentary strand
De novo
Anew; afresh; beginning again; from the start; ''de novo'' synthesis of a complex molecule, which refers to the biochemical pathway where a complex biomolecule is synthesized anew from simple molecules.
Leading Strand
The new complimentary DNA strand synthesized continuously along the template strand toward the replication fork in the mandatory 5' - 3' direction
Lagging Strand
A discontinuously synthesized DNA strand that elongates by means Okazaki fragments, each synthesized in the 5' - 3' direction, away from the replication fork
Okazaki fragment
A short segment of DNA synthesized away from the replication fork on a template strand during DNA replication; joined together to make up the lagging strand of newly synthesized DNA
"Central Dogma"
DNA to RNA to Protein (Amino Acid)
DNA encodes genes, which are transcribed into mRNA, and then translated into protein
Transcription
The synthesis of RNA using a DNA template
Translation
The synthesis of a polypeptide using the genetic info encoded in a mRNA molecule; from nucleotides to amino acids
DNA/RNA
Deoxyribonucleic acid
Ribonucleic acid
RNA Polymerase
An enzyme that links ribonucleotides into a growing RNA chain during transcription, based on complimentary binding to nucleotides on a DNA template strand
Codon
A 3 nucleotide sequence of DNA or mRNA that specifies a particular amino acid or terminal signal
Intron
A noncoding, intervening sequence within a primary transcript that removed from the transcript during RNA processing ; region of DNA where this sequence was transcribed
tRNA
Transfer RNA; An RNA molecule that functions as a translator between nucleic acid and protein languages by carrying out specific amino acids to the ribosome, where they recognize the appropriate codons in the mRNA
mRNA
Messenger RNA; A type of RNA synthesized using a DNA template that attaches to the ribosomes in the cytoplasm and specifies the primary structure of a protein
Aminoacyl-tRNA synthetase
An enzyme that joins each amino acid to the appropriate tRNA
Ribosome
A complex of rRNA and protein molecules that function as a site of protein synthesis in the cytoplasm; has a small and large subunit
A site
The ribosomal site most frequently occupied by aminoacyl-tRNA. The aminoacyl-tRNA in the A-site functions as the acceptor for the growing protein during peptide bond formation.
P site
The ribosomal site most frequently occupied by peptidyl-tRNA, i.e. the tRNA carrying the growing peptide chain. The P-site is also referred to as the puromycin sensitive site. Puromycin is an antibiotic which shows similarities with a part of aminoacyl-tRNA. When puromycin is present in the A-site, the peptide can be linked to puromycin via a peptide bond. Thus, peptidyl-tRNA in the P-site is located in the puromycin sensitive site
E site
She ribosomal site harbouring decylated tRNA on transit out from the ribosome; Exit Site
Differentiated cell
The process by which a cell becomes specialized in order to perform a specific function, as in the case of a liver cell, a blood cell, or a neuron. There are more than 250 general types of cells in the human body.
Cloning
A type of asexual reproduction, where the offspring is genetically identical to the parent
Lac operon
(lactose operon) is an operon required for the transport and metabolism of lactose in Escherichia coli and many other enteric bacteria. Although glucose is the preferred carbon source for most bacteria, the lac operon allows for the effective digestion of lactose when glucose is not available; Promoter, operator, and coordinately regulated cluster of genes
Transcription factor
True or false: When Mendel carried out di-hybrid crosses, he found that pea phenotypes were found in a ratio of 9 yellow and round (both traits are dominant), 3 yellow and wrinkled, 3 green and round, and 1 green and wrinkled both traits are recessive). In other words, he found a 9:3:3:1 ratio. He also found that a single trait (color or shape) still followed a 3:1 ratio of dominant phenotype to recessive phenotype.
True
Imagine that you are studying a trait that has more than 2 phenotypes in a population (i.e., blood type, dog coat color, etc.) Describe at least two ways that geneticists could explain such a trait (we discussed 4).
Incomplete dominance (as seen in blending), multiple alleles for a gene (i.e., blood type), multiple genes for a trait (polygenic), or environmental influence on a gene (multifactorial trait).
Describe one experiment that demonstrated that DNA rather than protein is the genetic molecule.
Transformation of bacteria, in which non-lethal bacteria acquired a lethal trait due to growing in the presence of the remains of lethal bacteria. Avery et al. showed that it is specifically DNA that is required for transformation.
Tracing of virus protein and DNA shows that DNA (not protein) is what enters infected cells, causing new viruses to be generated.
Describe how the model of DNA that Watson and Crick proposed satisfies both of Chargaff's rules, and Rosalind Franklin's data.
The anti-parallel, complimentary nature of DNA satisfies both sets of criteria. Chargaff's findings that A and T exist in a 1:1 ratio, and G and C exist in a 1:1 ratio, but that each can change is explained by the complimentary nature of nucleotides because A pairs with T, and G pairs with C, but the order of nucleotides on one strand are independent from one another. This arrangement also satisfies Franklin's data, because for the bases to fit together in a complimentary fashion, they form helices that wind around each other, making a uniform molecular structure.
Why must life use at least 3 nucleotides to code for the 20 different amino acids?
1 nucleotide per amino acid only would allow 4 kinds of amino acids. 2 nucleotides/amino acid only allows 16 (4X4), 3 nucleotides results in 64 possible combinations, which is much more than 20.
What direction does RNA polymerase move along the TEMPLATE strand?
3'-5'; The newly synthesized strand is build in the 5'- 3 - direction but the polymerase enzyme will move along the template strand in the 3'-5' direction because complimentary strands run anti-parallel to each other
True or false: The function of some genes is to regulate the expression of other genes.
True
True or false: Meiosis is sufficient to explain the patterns of inheritance that Mendel observed
True
True or false: Among other accomplishments, Thomas Morgan demonstrated that genes are held on chromosomes
True
What animal did Thomas Morgan work with as a model organism for his research?
