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81 Cards in this Set
- Front
- Back
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What are the types of nucleotides?
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Adenine, Thymine, Cytosine, Guanine
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Which nucleotides are purines? Pyrimidines?
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Purines: Adenine & Guanine
Pyrimidines: Cytosine & Thymine |
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What is Chargaff’s rule?
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DNA as a regular structure where there are equal amounts of Adenine and Thymine and equal amounts of Cytosine and Guanine (A=T , G=C)
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How are DNA strands held together?
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Hydrogen Bonds
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How do the DNA strands of a double helix relate to one another?
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They are Complementary to one another which allows it to copy itself during cell division.
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What is gene expression?
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The process in which an RNA copy of each active gene is made, and the RNA copy directs the sequential assembly of a chain of amino acids at a ribosome.
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What is transcription? Where does it take place?
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The conversion of DNA to mRNA. Takes place in the Nucleus.
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What is mRNA?
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mRNA (Messenger RNA) The RNA copy of a gene used in the ell to produce a polypeptide. It conveys the information from the Nucleus to the Cytoplasm.
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What is translation? Where does it take place?
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The conversion of mRNA to Protein. mRNA is read by a ribosome in 3-nucleotide units. Takes place in the Ribosomes in the cytoplasm where the mRNA produced y transcription is directed y the ribosomes to produce proteins.
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What is a codon?
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The basic unit of the genetic code. A sequence of three adjacent nucleotides in DNA or mRNA that codes for one amino acid or for polypeptide termination.
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What is the intermediate molecule between DNA and a protein?
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mRNA
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Be able to take a DNA molecule and produce a complementary strand, mRNA molecule, and polypeptide chain
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Be able to take a DNA molecule and produce a complementary strand, mRNA molecule, and polypeptide chain
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What is a mutation?
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A change in the cell's genetic message.
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What is recombination?
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The formation of new gene combinations.
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When are mutations passed to offspring?
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Mutations are only passed on to future generations if they occur in the Germ Cells. (Natural Selection)
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What are point mutations?
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A single changed based pair in the DNA of an organism.
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What are base-substitution mutations?
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A type of mutation involving replacement or substitution of a single nucleotide base with another in DNA or RNA molecule.
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What are frame-shift mutations?
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The addition or deletion of nucleotides causes a shift in the reading frame of the codons in the mRNA, thus, may eventually lead to the alteration in the amino acid sequence at protein translation.
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What are transversions?
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A substitution mutation in which a purine is replaced by a pyrimidine, or a pyrimidine is replaced by a purine. ( A- C or T , G- C or T)
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What are transitions?
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A substitution mutation in which a purine is replaced by another purine or a pyrimidine with another pyrimidine. ( A-G C-T)
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What is a silent mutation?
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When a base change occurs but the same amino acid is coed, or when there is an amino acid substitution in the protein which has no detectable effect on the phenotype.
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What is a missense mutation?
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When an amino acid substitution occurs in the protein (1st or 2nd)
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What is a nonsense mutation?
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When a stop codon is substituted for a codon that specifies an amino acid.
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What is an insertion mutation?
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Results from the addition of extra nucleotides in a DNA sequence or chromosome.
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What is a deletion mutation?
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A type of mutation resulting from the deletion of nucleotides in a DNA sequence of nucleotides.
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What is transposition?
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Transfer of segment of DNA to a new position on the same or another chromosome.
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What are homologous chromosomes?
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One of 2 nearly identical versions of each chromosome (from parents). Chromosomes that associate in pairs in the first stage of meiosis. In diploid cells, 1 chromosome of a pair that carries equivalent genes.
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What is diploid? Haploid?
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A cell, tissue, or individual with a double set of chromosomes (2n)
Having one the set of chromosomes (n or 23 chromosomes) |
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What are sister chromatids?
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Two identical strands joined by a common centromere as a result of a chromosome that duplicated during the S phase of the cell cycle.
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What is chromatin?
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The complex of DNA and proteins of which eukaryotic chromosomes are composed (strand of DNA).
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What is mitosis?
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The mechanism of cell division that occurs in an organism's somatic (non-sex) cells.
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What are the stages of mitosis? Explain each stage, and what happens to the genetic information during each stage?
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the nuclear membrane disappears; chromatin condenses into chromatid
Chromosomes align on the equatorial plane sister chromatids separate and are pulled to the opposite poles nuclear envelope reappears; chromatids uncoil into chromatin |
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What is cytokinesis?
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When the cytoplasm divides and the cell is cleaved into two halves, resulting in two identical daughter cells.
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What is cancer? How does it occur?
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Unrestrained invasive cell growth, and cell division. (uncontrolled cell division) When cells grow and divide uncontrollably, spreading to other parts of the body forming tumors. Cancer results from damaged genes that fail to control cell division.
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What is meiosis?
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The division of DNA in an organism’s germ (sex) cells.
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What are gametes/germ cells?
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sex cells = gametes = germ-line cells
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What are somatic cells?
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Somatic cells are non-sex cells.
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What is the end product of meiosis?
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four non-identical sex cells
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What are the phases of meiosis I? What happens to the genetic material in each phase?
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Prophase 1 - nuclear membrane disappears, chromatin condenses into homologous chromosomes, crossing over occurs
Metaphase 1 - Homologous chromosomes line up on the metaphase plane Anaphase 1 -Homologous chromosomes are pulled to opposite poles of cell Telophase 1 - nuclear membrane reappears, chromosomes uncoil into chromatin |
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What are the phases of meiosis II? What happens to the genetic material in each phase?
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Prophase II - nuclear membrane disappears, chromatin condenses into chromatid
Metaphase II- chromosomes line up on the metaphase plane Anaphase II- chromatids are pulled towards the poles Telophase II - nuclear membrane reappears, chromatid uncoils into chromatin |
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What is crossing over? When does crossing over occur?
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When nonsister chromatids exchange portions of DNA strands. Crossing over occurs in Prophase I.
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What are the differences between Meiosis I and Meiosis II?
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synapsis (crossing over) and reduction divisions
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What is synapsis?
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(crossing over) The close pairing of homologous chromosomes that occurs early in prophase I of meiosis. Because the genes of the chromosomes are aligned, a DNA from one strand of one homologue can pair with the complementary DNA strand of the other.
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What is reduction division?
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When homologous chromosomes don’t replicate prior to meiosis II. The resulting cells are all haploid and consist of separated sister chromatids.
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What are the causes of genetic diversity?
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Independent assortment. Crossing over. Random fertilization.
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What is independent assortment?
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Formation of random combinations of chromosomes in meiosis and of genes on different pairs of homologous chromosomes.
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What is random fertilization?
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the egg that descends from the ovary is random and the sperm that fertilizes the egg is random
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What are the human female sex chromosomes? Male chromosomes?
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Females (XX) give the X chromosome. Males (XY) give the Y or X chromosome.
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What are the bird female sex chromosomes? Male chromosomes?
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Males (ZZ) give the Z chromosome. Females (WZ) give the W or Z chromosome
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What is unique about female and male insect chromosomes?
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Worker are both Male and Female. Males have 1 chromosome. Females have 2 chromosomes. Males are haploid, Females are diploid.
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What is temperature dependent sex determination? What organism uses this method?
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Turtles use temperature dependent sex determination.Temperature of sand surrounding eggs determines sex.
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How do females and males result?
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Cool Sand gives Males. Hot sand Gives Females.
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What is a karyotype?
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The chromosomes of a cell, usually displayed as a systematized arrangement of chromosome pairs in descending order of size. They are examined to detect genetic abnormalities, typically in extra or lost chromosomes.
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What is non-disjunction?
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Failure of homologous chromosomes to separate reequent to metaphase in meiosis or mitosis so that 1 daughter cell has both and the other neither of the chromosomes.
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What are dominant alleles?
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The 1 of the pair of alternative alleles that masks the effect of the other when both are present in the same cell or organism.
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What are recessive alleles?
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That 1 of the pair of alternative alleles whose effect is masked by the activity of the 2nd when both are present in the same cell or organism.
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What are homozygous?
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Relating to a cell that has 2 identical (same) alleles for a particular trait at corresponding positions on homologous chromosomes.
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What are heterozygous?
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Relating to a cell that has 2 different alleles at corresponding positions on homologous chromosomes.
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What are genotype and phenotype?
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The total set of genes present in the cells of an organism.
The observable expression of a trait that results from the biological activity of proteins or RNA molecules transcribed from DNA. |
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What is true breeding?
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A kind of breeding in which the parents with a particular phenotype produce offspring only with the same phenotype.
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What are the P generations?
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The 1st set of parents crossed in which their genotype is the basis for predicting the genotype of their offspring.
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What is an F1 Generation?
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(Felio) The 1st filial generation, which is comprised of offspring resulting from a cross of the 1st set of parents (parental generation)
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What are F2 Generations?
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The 2nd filial generation, which is comprised of offspring resulting from a cross of the members of F1 generation
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What is a dihybrid? What is a dihybrid cross?
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The offspring of 2 individuals that differ with respect to 2 pairs of genes (traits)
Dihybrid Cross: Hybridization using 2 traits with 2 alleles each. |
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What is a test cross? When are they used?
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A mating in which a homozygous recessive individual is bred with individuals of unknown genotype, but show the dominant phenotype.
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What are the traits/phenotypes that lack Mendelian inheritance (HINT: there are 5)
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continuous variation, pleiotropy, incomplete dominance, co dominant, environmental effect
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What is polygenic?
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Any of a group of nonallelic genes that collectively control the inheritance of a quantitative character or modify the expression of a qualitative character.
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What is continuous variation? What is an example of continuous variation?
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Variation within a population in which a graded series of intermediate phenotypes falls between the extremes. If 1 gene controls a trait there are distinct categories for phenotype, if multiple genes control a trait they have a continuous variation.
Ex. human height |
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What is a pleiotropic effect? What is an example of a pleiotropic effect?
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(Opposite of Polygenic) Characteristics of many inherited disorders. Examples, sickle-cell anemia which is a clotting disorder; round red blood cells to crescent sized.
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What is incomplete dominance? What is an example if incomplete dominance?
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The ability of 2 alleles to produce a heterozygous phenotype that is different from either homozygous phenotype. Example: Snapdragons, red and white flowers produce pink flowers
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What is environmental influence? What is an example of environmental influence?
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The degree to which many alleles are expressed depends on the environment. Traits influenced by the environment are more sensitive to temperature or light than other alleles. Example, coat color in foxes
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What is codominance? What is an example of codominance?
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(Opposite of incomplete dominance) Both alleles at a particular locus are apparent in the phenotype of the heterozygote. Example, ABO blood groups.
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What is a sex-linked trait?
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(X-Linked Traits) A trait determined by a gene on the sex chromosome.
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What sex is more likely to have a sex-linked trait?
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Males
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On what chromosome is the sex-linked trait carried?
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X Chromosome
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What is a carrier?
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(Always Heterozygous) An organism that carries a gene for a trait but does not show the trait itself.
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When do males express a sex-linked trait? When do females express a sex linked trait?
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Males express a sex-linked trait by it just being present. Females express a sex-linked trait, by being homozygous.
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What is an autosome?
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Any chromosome that is not a sex chromosome.
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What is a pedigree?
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A type of family tree that maps the occurrence of a trait in a family.
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How are males, females, and affected individuals represented in a pedigree?
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Males are represented by a square, Females a circle, and affected individuals are shaded
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What characteristics allow you to determine to pedigree type (trait type)?
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Autosomal dominant - one parent must be affected
Autosomal recessive - parents do not need to be affected, but must be heterozygous Sex-linked dominant - more common in females Sex-linked recessive - more common in males |
