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Embed code for: Chapter 13-17
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Gametes: sex cells
Autosomes: non sex chromosomes
Homologs (homo. chro.): carry same genes
Genes: sections of DNA w/one or more traits
Allele: different forms of genes
Egg: Female gamete (n)
Sperm: male gamete (n)
Zygote: diploid cell resulting from the fusion of two haploid gametes
Haploid: one of each type of chromosome (n)
Diploid: 2 of each type of chromosome (2n)
Karyotype: shape, size, number of chromosome
Sister chromatids: 2 identical chromatid copies in replicated chromosome.
Tetrads: homologous chromosome pairs
Crossing over: genetic recombination; tetrads break and exchange pieces
Independent assortment: alleles of same gene segregates independently
“crossing over is the process of exchange of DNA between homologous chromosomes whereas the independent assortment is the process in which the chromosome pairs align themselves at the middle of the cell”
Metaphase plate: plane in which chromosomes line up
Cytokinesis: division of cytoplasm to form daughter cells
Clone: individual who is genetically identical
Synapsis: physical pairing of 2 homologous chromosomes during prophase 1. Crossing over happens during
Humans: n=23, 2n=46 flies: n=4, 2n=8
Errors possible: chromosomes fail to separate in meiosis 1, gametes will have an extra chromosome of will lack chromosomes (aneuploidy)
Nondisjunction- down syndrome and trisomy
Genes: segments of DNA that code for a specific protein
Locus: “address’ of the gene
Trait: characteristic of the organism
Dominant allele: only needs one of them to give trait it codes for
Recessive allele: needs 2 copies of recessive to show
Homozygous: homologous chromosomes having 2 of same allele
Genotype: actual alleles present on chromosomes
Phenotype: physical appearance of organism
Heterozygous: homologous chromosomes having 2 different alleles
Heredity: transmission of traits from parents to offspring
Model organism: species used for research b/c it’s practical and conclusions apply to other organisms.
X-linked: gene located on X chromosome
Autosomal: gene located on any non-sex chromosome or trait determined by autosomal gene
F1 generation: offspring of parental generation
Incomplete dominance: heterozygote phenotype in between homozygote phenotypes
Codon: sequence of 3 nucleotides in DNA or RNA that code for amino acid
Principle of segregation: 2 members of each gene pair must segregate into different gamete cells during formation of egg and sperm. Result: each
gamete contains one allele of each gene.
Pease have 2 copies of each gene and thus may have 2 different alleles of the gene
Tis also turns out to be true for many other organisms
Genes are particles of inheritance that do not blend together
Genes maintain their integrity from generation to generation
Each gamete contains 1 copy of each gene (one allele)
B/c of principle of segregation- members of each gene pair segreg.
Males and females contribute equally to genotype of offspring
When gametes fuse, offspring acquire total of 2 of each gene
Some alleles r dominant to others
Has dominant and recessive – individual has dominant phenotyp
Chromosome theory of inheritance: states that Mendel’s rules can be explained by independent alignment and separation of homologous chromosomes at meiosis 1.
Independent assortment: alleles of different genes are transmitted independently of one another.
Sex linked traits: if eye color is on X chromosome, females have 2, males have 1
Linked genes don’t assort independently. Linked genes are inherited together unless cross over occurs between them (genetic recombination).
Environment on phenotype: Tempurature, sunlight, nutrient availability, competition, mother hormone levels
Discrete traits: traits clearly different from e/o; no intermediate; yellow/green
Quantitative: continuously varying traits; no distinct categories; height; intelligence
Replisome: molecular machine composed of primase, topo, DNA polymerases, SSBPs, and helicase.
Helicase: proteins that open DNA by breaking H bonds between bases
Topoisomerase: protein that relieves twisting forces as DNA unwinds
SSBPs: protein that stabilizes single strands
Leading strand synthesis…
DNA polymerase(3): protein that synthesizes new DNA strand
Sliding clamp: holds DNA polymerase in place
Primase: catalyzes synthesis of RNA primer
DNA ligase: Catalyzes joining of okazaki fragments
Sliding Clamp, pimase. DNA polymerase 1 and 2
Semiconservative: each newly made DNA molecule made of 1 old 1 new strand
Genome: entire complement of DNA
Okazaki fragments: short DNA fragments in lagging strand
Telomere: region at end of eukaryotic chrom.
Telomerase: catalyzes synthesis of DNA from RNA template. Adds DNA to end of chromosome preventing it from shortening. Only in gametes
RNA polymerase: enzyme that catalyzes synthesis of RNA using DNA template
Discontinuous replication: primase synthesizes new RNA primers for lagging strands
Eukaryotic: multiple origins; linear
Bacterial: 1 origin; circular; easier
Leading: continuous; DNA polymerase 3
Lagging: Okazaki fragments; discontinuous; DNA polymerase 3 and 1; DNA ligase to join fragments
Problem w/telomere: in lagging strand, no DNA synthesis occurs after primer is removed; unreplicated end will degrade, shortening chro
Solution: Telomerase extends unreplicated end; provides room for RNA primer; fill in missing DNA
Mismatch: DNA polymerase detects and corrects by removing base and adding base
Nucleotide excision: workd on DNA damage caused by UV and chemicals. Fixes thymine dimers and damage that distort DNA helix
Transcription: copying of DNA to RNA (RNA poly)
Translation: using information in nucleic acids to synthesize proteins (RNA to proteins) Central dogma:
mRNA: messenger RNA; carries info out of nucleus from DNA to site of protein synthesis
Central dogma: flow of info in cells. DNA codes for RNA which codes for proteinsarch b/c it’s practical and conclusions apply to other organisms.