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35 Cards in this Set
- Front
- Back
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What is the Definition of a Genome? |
The complete haploid genetic information of a cell or organism, DNA that contains that information -Human genome = 3.2 billion bp |
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Eukaryotic Chromosomes |
Chromosomes: DNA and proteins DNA stretched out = 2 meters long DNA must be packaged to fit inside nucleus of cell |
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What are the three elements of a chromosome? |
Telomere: Caps on tails of DNA Replication Origin: Can be multiple Centromere: heterochromatic region where kinetochore assembles. Links sister chromatids in the middle of the X where they link |
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DNA packaging |
46 chromosomes total 22 from father 22 from mother 2 sex chromosomes Chromosomes are made from chromatin. |
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Homologs |
2 copies, diploid, "homologous chromosomes" |
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Compacation |
DNA wraps around histone for a "bead on a string" model. Compacts DNA X3. Histone located in center with two wraps of DNA arround it. Negative charge DNA attracted to pos of histone |
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Nucleosome Structure |
"Beads on a string" form of chromatin Core histones of nucleosome (200 pb of DNA) Nuclease digests linker DNA which releases nucleosome. (11 nm). Dissociation into octameric histone core, 146-nucleotide-pair double helix. Histone core dissociated into H2A, H2B, H3 and H4 (X2 of all) |
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The 30 nm fiber |
Nucleosome units made into 30 nm fiber. Compaction X7
Structure hard to determine, DNA may be altered when extracted Requires Histone 1 (H1). Attaches to DNA to link histone cores together (compaction) - creates zig-zag model |
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Final stage of condensation |
Occurs at mitosis DNA is compacted 10,000 X original DNA strand Ends as 1400 nm in length compared to original 2 nm of naked DNA |
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What is Heterochromatin? |
Type of compaction: - Highly compact and transcriptionally inactive - localized regions in nondividing cells (centromeres and telomeres) |
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What is Euchromatin?
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Type of compaction: - Less condensed, capable of gene transcription - Located in most regions of non-dividing cells (Turn into heterochromatin once divided) |
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Histone Tail |
Histones not perfectly circular due to tail Modification usually on N-terminus. Includes: - Acetylation - Phosphorylation - Methylation - Ubiquitination |
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Homologues |
Species that is diploid, Members of a pair of chromosomes One from Mother One from Father Contain same genes but different alleles |
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Mitotic Cell Division |
- Cell divides to produce two new cells, genetically identical -Mother: Daughter + Daughter |
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The Cell Cycle of Mitosis |
1. Interphase ( G1, S, G2) 2. Mitosis: - Prophase - Prometaphase - Metaphase - Anaphase - Telophase - Cytokinesis |
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Mitosis |
Sorting process, each daughter cells gets correct number/ type of chromosomes |
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Mitotic Spindle |
Responsible for organizing and sorting the chromosomes |
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Centrosomes |
Microtubule organizing center -Come from mitotic spindle |
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What are the different microtubules? |
-Astral -Polar -Kinetochore |
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Prophase and Prometaphase |
Chromosomes condense Nuclear envelope breaks down Mitotic spindle forms centrosomes move apart. go to two poles Spindle fibers interact with sister chromatids Kinetochores on sister attach to kinetochore on poles |
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Metaphase |
Chromosomes are aligned along metaphase plate |
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Anaphase |
Chromosomes segregate to opposite poles |
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Telophase |
Chromosomes at opposite poles. Membrane forms |
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Cytokinesis |
Cell divides (Different for plants/ animals) - Animals: Cleavage furrows - Plants: Cell wall forms in center of cell. Expands toward edges until it divides |
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Meiosis |
Sexual reproduction. Requires fertilization event. Two haploid gamates unite to create diploid cell called zygote. -Meiosis: Process by which haploid cells are produced from cell originally diploid |
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Mitosis vs Meiosis |
Mitosis: Chromosomes singly line up at the metaphase plate. Meosis: Pair before lining up at the metaphase plate |
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Zygote |
Diploid cell: two haploid gamates unite |
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Bivalent |
Homologous pairs of sister chromatids. lying side by side to form bivalent (tetrad). Process called synapsis |
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Crossing Over |
Physical exchange between homologous within a bivalent Required for correct segregation of homologous in most species Increases genetic variation Chiasma: Cytologically observable site of crossover in bivalent |
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Haploid Dominant Species |
Multicellular organism is haploid Many fungi and protists |
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Diploid Dominant Species |
Most animal species Haploid gametes are a specialized type of cell |
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Name a few chromosomal mutations |
Deletions: segments missing Duplications: Section occurs 2 or more times in a row Inversions: Self-explanatory Translocations: One segment becomes attached to another chromosome |
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Aneuploidy |
Alternation in number of particular chromosomes Total number not an exact multiple of a set |
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Trisomic |
Normal 2 copies of a chromosome plus a 3rd 2n + 1, Trisomy 21 |
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Monosomic |
Missing one of normal copies of a chromosome 2n - 1, XO |
