Biol 230 Midterm #2 Flashcards
Define: Aflatoxin
A family of carcinogen, poison, and mutagens, that are produced by certain molds.
Can create a DNA adduct on a guanine nucleotide that can lead to cancer due to a loss of function is p53 (tumor suppressor gene).
Explain: DNA Replication
The first step of the central dogma.
Helices unzips the DNA strands.
The DNA polymerase enzyme travels along the DNA strand, creating a complementary strand from the 5’ to the 3’ end.
Both strands serve as template for the complementary strands to replicate from.
The leading strand (towards the fork) and lagging strand (away from the fork) are replicated differently.
Define: DNA polymerase
DNA polymerase (DNAP) is a type of enzyme that is responsible for forming new copies of DNA, in the form of nucleic acid molecules.
Reads DNA from the 3’ to 5’ ends.
Synthesizes DNA from the 5’ to 3’ ends.
Define: p53
Tumor suppressor gene.
It can activate DNA repair proteins when DNA has sustained damage
It can arrest growth by holding the cell cycle at the G1/S regulation point on DNA damage recognition. (Slows cell growth)
It can initiate apoptosis (i.e., programmed cell death) if DNA damage proves to be irreparable.
It is essential for the senescence response to short telomeres.
Many cancers are a result of a mutation in this gene.
Define: Translation
The process of translating the sequence of a messenger RNA (mRNA) molecule to a sequence of amino acids.
Define: Acquired mutation
A mutation that has been acquired during the lifetime of the organism.
Not inherited.
Define: Colon cancer
Unregulated growth of cells that begins in a part of the large intestine called the colon.
Define: Polyp
A small growth, usually benign and with a stalk, protruding from a mucous membrane.
Define: APC gene
Tumor suppressor gene.
Define: Inherited mutation
A mutation that has been inherited, from ‘parent’ to ‘offspring’.
Mutations like these must be acquired in the gametes, in order to be passed down through generations.
Not acquired.
Explain: Cell cycle
Mitosis, Cytokinesis, Interphase (G1, S, G2. (G0)).
Explain: Transcription
Transcription is the process of copying a segment of DNA to synthesize RNA.
Define: DNA Adduct
A DNA nucleotide covalently bonded to a chemical. (safrole, benzopyrenediol epoxide, acetaldehyde).
Define: Sister-chromatids
The two identical chromatids that are formed by replication of a chromosome during the S phase of the cell
Deine: Homologous Pairs
A pair of matching chromosomes in an organism, with one being inherited from each parent.
Explain: S phase of cell cycle
When DNA replication occurs.
S for sister.
Explain: M phase of cell cycle
The phase where division occurs, containing mitosis and cytokinesis.
Explain: Mitosis
The process by which a somatic cell is duplicated. (Copy machine)
‘Produces’ two similar diploid cells.
PPMAT
Define: Diploid
Containing two complete sets of chromosomes, one from each parent.
Explain: Meiosis
The process by which germ line cells are produced. (Slot machine)
‘Produces’ four randomized haploid cells.
Crossing over.
Random Assortment.
Meiosis I and Meiosis II.
Explain: Law of segregation
Alleles segregate randomly into gametes.
Explain: Copy machine
Mitosis is considered the copy machine, because it’s ‘goal’ is to create exact copies.
Define: Haploid
Having a single set of unpaired chromosomes.
Define: Gametes
A mature haploid male or female germ cell which is able to unite with another of the opposite sex in sexual reproduction to form a zygote.
Explain: Slot machine
Meiosis is referred to as the slot machine, because its ‘goal’ is to combine genetic information in a random fashion to create genetic variation. The outcome of which could be looked at as a slot machine.
Define: Autosome
Any chromosome that is NOT a sex chromosome.
Define: X chromosome
One of the two sex chromosomes that are involved in sex determination. Humans and most other mammals have two sex chromosomes (X and Y)
Define: Sex chromosome
In humans they are XY in males or XX in females. These determine the sex of the organism.
Define: Germ line cells
Gametes
Define: Somatic cells
Every other cell other than the germ line cells.
Define: Stem cells
An undifferentiated cell of a multicellular organism which is capable of giving rise to indefinitely more cells of the same type.
Define: Specialized cells
Cells with unique structures and functions in the body.
Define: Differentiated cells
When a cell changes form and / or function.
Explain: Cell division
In mitosis the process by which a ‘parent’ cell divides into two ‘daughter’ cells.
In meiosis the process by which a ‘parent’ cell divides into four ‘daughter’ cells.
Define: Y chromosome
A sex chromosome which is normally present only in male cells, which are designated XY.
Define: Random fertilization
Male gamete and female gamete that fuse to produce an offspring are selected randomly from the pool of male and female gametes.
Define: Independent assortment
How different genes independently separate from one another when reproductive cells develop.
Takes place in during metaphase I of meiotic division.
Define: Gregor Mendel
Discovered laws of inheritance when studying pea plants.
Define: Genotype
The genetic constitution of an individual organism.
Define: Phenotype
The set of observable characteristics of an individual resulting from the interaction of its genotype with the environment.
Define: Punnet square
A tool that helps to show all possible allelic combinations of gametes in a cross of parents with known genotypes.
Named after Reginald C. Punnett, who devised it in 1905.
Define: Dominant
A gene or allele that is expressed over a recessive gene, due to a gain of function mutation in the dominant gene, or a loss of function in the recessive gene.
Define: Homozygous
Having two identical alleles of a particular gene or genes.
Define: Heterozygote
An individual having two different alleles of a particular gene or genes.
Define: Polygenic trait
A characteristic, such as height or skin color, that is influenced by two or more genes.
Define: Recessive
A gene that is not fully expressed usually as a result of a loss of function mutation.
The trait is only expressed when the organism is homozygous with two of these alleles.
Define: Homozygote
An individual having two identical alleles of a particular gene or genes.
Define: Heterozygous
Having different alleles for a particular gene or genes.
Define: Monogenetic trait
A monogenic trait is a trait produced by the effect of a gene or an allele. It is in contrast to a polygenic trait that is controlled by a polygene (multiple genes).
Define: Alleles
One of two or more alternative forms of a gene that arise by mutation and are found at the same place on a chromosome.
Define: Dimer
UV light disrupts hydrogen bonds, causing two adjacent thymine nucleotides to bond covalently.
A ‘kink’ in the DNA.
Define: Aspergillus flavis
A fungus that grows on nuts and grains in hot and humid environments.
Can produce aflatoxin.
Can cause liver cancer.
Explain: Prophase
Nuclear membrane breakdown followed by condensation of the chromosomes and separation of the centrosomes.
Explain: Pro-metaphase
Formation of mitotic spindles, which are attached on one end to the centrosomes, and at the other end to the kinetochore, a protein structure located at or near the centromeres of mitotic chromosomes.
Explain: Metaphase
Chromosomes congregate at the equatorial plate.
Explain: Anaphase
Chromosomes are pulled to opposite poles.
Explain: Telophase
Formation of new nuclear membranes around the daughter nuclei and uncoiling of the chromosomes.
Explain: Cytokinesis
Formation of a cleavage furrow that leads to the formation of two daughter cells.
Divides the nuclei, cytoplasm, organelles and cell membrane into two cells containing roughly equal shares of these cellular components.
Explain: G1 Phase
Cell grows and functions normally.
High amount of protein synthesis occurs and the cell grows to about double its original size.
(Grow 1)
Explain: S Phase
Cell synthesizes its DNA and the amount of DNA is doubled but the number of chromosomes remains constant.
(Synthesis)
Explain: G2 Phase
The mitochondria divide and the cell continues to grow until mitosis begins.
(Grow 2)
Explain: G0 Phase
The cell is not replicating.
Define: Chromatin
‘Stringy’ uncoiled DNA.
