Mutations can affect protein structure and function Mutations are changes in

Mutations can affect protein structure and function

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Mutations can affect protein structure and function - Mutations are changes in the genetic info of a cell - Point mutation are changes in just one nucleotide pair of a gene - The change of a single nucleotide in a DNA template strand can lead to the production of an abnormal protein Substitutions - A nucleotide pair substitution replaces one nucleotide and its partner with another pair of nucleotides - Silent mutations have no effect on the amino acid produced by a codon because of a redundancy in the genetic code - Missense mutations still code for an amino acid, but not the correct amino acid - Nonsense mutations change an amino acid codon into a stop codon; most lead to a nonfunctional protein Meiosis and Mitosis Interphase: G1 Phase (‘first gap”) S Phase (‘synthesis” chromosome duplication) G2Phase (growing) Mitosis is conventionally broken down into 5 stages - Prophase - Prometaphase - Metaphase - Anaphase - Telophase Differences between meiosis and mitosis - Meiosis has 2 cycles - Mitosis makes identical cells (daughter cells); meiosis makes unique daughter cells - Mitosis has diploid (2n) daughter cells; meiosis has haploid (n) daughter cells - Meiosis produces gametes (sperm and egg) (23 chromosomes); mitosis produces somatic cells (body cells) (46 chromosomes) - Zygote: fertilized egg - Mitosis produces 2 daughter cells; meiosis produces 4 - Meiosis has crossing over during PROPHASE 1 - Tetrads prophase of meiosis Cellular organization of the genetic material - All the DNA in a cell constitutes the cells genome - DNA molecules in a cell are packaged into chromosomes Background and VOCAB - In prep for cell division, DNA is replicated and the chromosomes condense - Each duplicated chromosome has 2 sister chromatids (joined copies of the original chromosome) - The centromere is the narrow “waist” of chromosomes where the 2 chromatids are most closely attached - The splitting of cytoplasm = cleavage furrow in animals
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- Cell plate in plants Cell spends 90% of its time in interphase The sequential events of the cell cycle are directed by a distinct cell cycle control systems direct cell cycle and have specific checkpoints A go-ahead signal at the G1 checkpoint usually means completing the S,G2, and M phases and dividing G0 phase: nondividing state Cancer cells avoid nondividing G0 phase so they spread uncontrollably Inheritance of Genes - Genes: units of heredity; segments of DNA - Gametes: sperm and eggs (23 chromosomes, italicized end: haploid #) (unite and fertilize ‘zygote’ =46 chromosomes) XX,XY determines sex (X is bigger) - Locus: a genes specific position along a chromosome Clicker Q: How many chromosomes do humans have in the nuclei of their somatic cells? 46 Clicker Q: Clones are a product of asexual reproduction Karyotypes and homologs - Sex chromosomes: determine the sex of the individual; X and Y 23 rd pair - Autosomes: remaining 22 pairs of chromosomes (ones that do not determine sex) - Fertilization: union of gametes (the sperm and the egg) -
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