BI 221 Final

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151 Terms

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cell cycle
series of events that cells go through as they grow and divide
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G1 checkpoint
Checks the surroundings to make sure the conditions are favorable and the cell is healthy enough to enter the next stage
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G2 checkpoint
The cell checks to make sure the DNA is copied correctly
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M checkpoint
Spindle assembly checkpoint. Mitosis will not continue if chromosomes are not properly aligned.
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benign tumor
A mass of abnormal cells with specific genetic and cellular changes such that the cells are not capable of surviving at a new site and generally remain at the site of the tumor's origin.
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malignant tumor
An abnormal tissue mass that can spread into neighboring tissue and to other parts of the body; a cancerous tumor.
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metastasis
spread of cancer cells beyond their original site in the body
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Proto-oncogenes
normal cellular genes that are important regulators of normal cellular processes, they promote growth.
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Oncogenes
mutated forms of proto-oncogenes that cause normal cells to grow out of control and become cancer cells
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tumor suppressor genes
A gene whose protein product inhibits cell division, thereby preventing the uncontrolled cell growth that contributes to cancer.
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Purine
a nitrogenous base that has a double-ring structure; one of the two general categories of nitrogenous bases found in DNA and RNA; either adenine or guanine
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Pyrimidines
a nitrogenous base that only has a single ring structure; one of the two general categories of nitrogenous bases found in DNA and RNA; either thymine, cytosine, or uracil
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Polymer
A long molecule consisting of many similar or identical monomers linked together.
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DNA backbone
5' to 3' phosphodiester bonds form phosphate backbone
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phosphodiester bond
the type of bond that links the nucleotides in DNA or RNA. joins the phosphate group of one nucleotide to the hydroxyl group on the sugar of another nucleotide
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semi-conservative replication
in each new DNA double helix, one strand is from the original molecule, and one strand is new
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conservative replication
Conservative replication is a theoretical method of replication where the original strands of DNA are left intact and two new strands are formed bonded together.
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dispersive replication
a disproved model of DNA synthesis suggesting more or less random interspersion of parental and new segments in daughter DNA molecules
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Primase
An enzyme that joins RNA nucleotides to make the primer using the parental DNA strand as a template.
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single strand binding proteins
bind to the unpaired DNA strands, keeping them from re-pairing
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Topoisomerase
Enzyme that functions in DNA replication, helping to relieve strain in the double helix ahead of the replication fork.
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DNA polymerase III
synthesizes new DNA only in the 5' to 3' direction
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DNA polymerase I
removes the RNA primer and replaces it with DNA
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DNA ligase
an enzyme that eventually joins the sugar-phosphate backbones of the Okazaki fragments
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Helicase
An enzyme that untwists the double helix of DNA at the replication forks.
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Okazaki fragments
Small fragments of DNA produced on the lagging strand during DNA replication, joined later by DNA ligase to form a complete strand.
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nucleotide triphosphate
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origin of replication
Site where the replication of a DNA molecule begins, consisting of a specific sequence of nucleotides.
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replication fork
A Y-shaped region on a replicating DNA molecule where new strands are growing.
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Centromere
Area where the chromatids of a chromosome are attached
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Euchromatin
The less condensed form of eukaryotic chromatin that is available for transcription.
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Heterochromatin
Eukaryotic chromatin that remains highly compacted during interphase and is generally not transcribed.
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Histones
protein molecules around which DNA is tightly coiled in chromatin
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Gamates
reproductive cells
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chromosome number
The total number of chromosomes in a cell of a given species.
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Karyotype
A display of the homologous chromosome pairs of a cell arranged by size and shape.
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somatic cells
body cells
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Ploidy
number of sets of chromosomes in a cell
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homologous chromosomes
Chromosomes that have the same sequence of genes, that have the same structure, and that pair during meiosis.
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Haploid
having a half set of chromosomes
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Diploid
2 sets of chromosomes
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asexual reproduction
A reproductive process that involves only one parent and produces offspring that are identical to the parent.
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sexual reproduction
Process by which cells from two different parents unite to produce the first cell of a new organism.
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Fertilization
Fusion of an egg and sperm cell
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crossing over
Process in which homologous chromosomes exchange portions of their chromatids during meiosis.
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chiasmata
site of crossing over
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synapsis
the fusion of chromosome pairs at the start of meiosis.
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Recombination
the genetic process by which one chromosome breaks off and attaches to another chromosome during reproductive cell division
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law of independent assortment
Each member of a pair of homologous chromosomes separates independently of the members of other pairs so the results are random
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recombinant chromosomes
A chromosome created when crossing over combines the DNA from two parents into a single chromosome.
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Allele
An alternative form of a gene.
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dihybrid cross
Cross or mating between organisms involving two pairs of contrasting traits
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Law of Dominance
In many traits one allele is dominant over the other allele. The "weaker recessive" allele is only expressed when it is paired with another recessive allele
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Genotype
genetic makeup of an organism
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Phenotype
An organism's physical appearance, or visible traits.
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Heterozygous
An organism that has two different alleles for a trait
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Homozygous
An organism that has two identical alleles for a trait
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Law of Segregation
Mendel's law that states that the pairs of homologous chromosomes separate in meiosis so that only one chromosome from each pair is present in each gamete
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locus
Location of a gene on a chromosome
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monohybrid cross
A cross between individuals that involves one pair of contrasting traits
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P generation
parent generation
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F1 generation
the first generation of offspring obtained from an experimental cross of two organisms
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F2 generation
the second generation of offspring, obtained from an experimental cross of two organisms; the offspring of the F1 generation
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progeny
offspring
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testcross
cross between an organism with an unknown genotype and an organism with a recessive phenotype
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true-breeding
term used to describe organisms that produce offspring identical to themselves if allowed to self-pollinate
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Pedigree
A diagram that shows the occurrence of a genetic trait in several generations of a family.
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product rule of probability
The chance of two or more independent events occurring together is the product of their chance of occurring separately
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sum rule of probability
the chance of an event that can occur in more than one way is the sum of the individual chances
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independent events
The outcome of one event does not affect the outcome of the second event
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mutually exclusive events
events that cannot happen at the same time
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Carrier
A person who has one recessive allele for a trait, but does not have the trait.
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plieotropy
The ability of a single gene to have multiple phenotypic effects.
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epistatis
gene at one locus on the chromosome alters the phenotypic expression of a gene at different locus
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Co-dominance
A pattern of inheritance in which the phenotypic effect of two alleles in a heterozygous genotype express each phenotype of each allele fully and equally; a phenotype which would not be expressed in any other genotypic combination.
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incomplete dominance
A pattern of inheritance in which two alleles, inherited from the parents, are neither dominant nor recessive. The resulting offspring have a phenotype that is a blending of the parental traits.
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polygenic inheritance
occurs when multiple genes determine the phenotype of a trait
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heterogametic
sex chromosomes are of different types
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homogametic
sex chromosomes are of one type
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sex linkage
the presence of a gene on a sex chromosome
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Autosomes
Any chromosome that is not a sex chromosome
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wildtype
the most common genotype/phenotype observed in a population
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X-linked
referring to a gene located on the X chromosome
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SRY gene
the sex determining region of the Y chromosome in males. Encodes the testis-determining factor, which turns the primordial gonads into the testes
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sex determination
The biological mechanism that determines whether an organism will develop as a male or female
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sex-limited traits
a characteristic controlled by autosomal genes that is phenotypically exhibited in only one of the two sexes.
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sex-influenced traits
an autosomal trait that is influenced by the presence of male or female sex hormones
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sex chromosomes
Chromosomes that determine the sex of an individual
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Nondisjunction
Error in meiosis in which homologous chromosomes fail to separate.
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nondisjunction in meiosis I
4 abnormal gametes, 2 with chromosome duplicated, 2 with corresponding chromosomes missing
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nondisjunction in meiosis II
2 normal gametes, 2 abnormal gametes
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Aneuploidy
Abnormal number of chromosomes.
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X inactivation
one of two X chromosomes is randomly inactivated and remains coiled as a Barr body
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Barr body
A dense body formed from a deactivated X chromosome.
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gene linkage
the tendency of DNA sequences that are close together on a chromosome to be inherited together during the meiosis phase of sexual reproduction
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Trisomy
3 copies of a chromosome
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recombinants
offspring whose phenotype differs from that of the parents
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recombination frequency
the percentage of recombinant offspring among the total. (number of recombinants/total number of offsprings)x100%
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Monosomy
Chromosomal abnormality consisting of the absence of one chromosome from the normal diploid number
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alternative splicing
Splicing of introns in a pre-mRNA that occurs in different ways, leading to different mRNAs that code for different proteins. Increases the diversity of proteins.