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45 Cards in this Set
- Front
- Back
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What are chromosome disorders?
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gain or loss of genes in whole chromosomes or segments of chromosomes (ex. extra copy of chromosome 21 = down syndrome).
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What are singe gene defects?
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Individual mutant genes. Mutation present on one or both chromosomes of the pair.
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What is multifactorial inheritance?
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The result form complex interactions between genetic and environmental factors.
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What is a gene map?
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It maps the chromosomal location of the genes.
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What is a karyotype?
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A species of specific characteristic chromosome complement (# and morphology).
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What are genes?
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Units of genetic information. ~25,000 structural genes organized along the chromosomes with precise location (locus).
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What are somatic cells?
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All the cells in the body except the gamete forming germline. Most are diploid.
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What are alleles?
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One of the alternate versions of a gene
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Mitochondrial genes exhibit what?
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Exclusively maternal inheritance
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What is the genome packaged as?
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Chromatin
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What is chromatin?
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DNA with chromosomal proteins (ex.. histone & non-histone proteins)
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What are the four core histones?
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H2A, H2B, H3, H4 (they come in pairs forming an octomer)
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Nucleosome
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basic structural unit of chromatin (appear as beads on a string)
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What can change the properties of the nucleosome?
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Post-translational modification of histones H3 & H4.
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What is the most common type of post-translational modification?
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Acetylation (this causes gene activation)
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Solenoid
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2ndary helical chromatin structure of coiled nucleosomes, appear as thick 30-nm cylindrical fiber
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Histone code
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Varies bt cell types to regulate gene expression (regulation bt histone interaction w/ DNA)
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During interphase of cell cycle...
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Chromosomes are in their most decondensed state (cells spend most of their time here)
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Single-copy DNA sequences
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Compose nearly 1/2 of genome (45%), function is a mystery. These are unique sequences that are dispersed throughout enome
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Dispersed repetitive DNA
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Compose ~45% of genome, do not cluster and contribute to the maintainance of chromosomal structure
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Pentanucleotide repeats
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Long arrays, example of a tandem repeat.
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Where are pentanucleotide repeats found?
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In genetically inert regions on chromosomes 1, 9,16 and more than half of the Y chromosome
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Alpha satellite family
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171 bp unit repeat found @ the centromere of each chromosome
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Alu family
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300 bp repetitive element, dispersed throughout the genome (compose ~10% of genome)
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LINE
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(Long interspersed nuclear element) up to 6kb long and ~850,000 copies ( ~20% of genome)
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Mitiosis
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Somatic cell division. Results in diploid daughter cells, 46 chromosomes IDENTICAL to parent cell
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Meiosis
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Only in germline cells (reproduction), results in gametes w/ 23 chromosomes genetically different from parent cells
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Which phases of mitosis make up intephase?
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G1, S, G2
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G1
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follows mitiosis, no DNA synthesis, can last for hours, days or years
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S phase
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stage of DNA synthesis
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Telomeres
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Specialized repetitive DNA sequences that ensure chromosome integrity during cell division. Maintained by telomerase
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5 stages of mitosis
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Prophase
Prometaphase Metaphase Anaphase Telophase |
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Chromosome segregation
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Process of distributing a copy of each chromosome to each daughter cell (summarizes mitosis)
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Congression
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Chromosomes move toward point midway bt spindle poles
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Centromere
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a region of DNA typically found near the middle of a chromosome where two identical sister chromatids come in contact
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Kinetochore
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Attaches chromosomes to microtubules of the mitotic spindle to govern their movement
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Chiasma
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Point where sister chromatids cross over
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Is DNA synthesis synchronous?
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NO!! Each chromosome has hundreds to thousands of origins of replication
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Prophase
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Initiates mitiosis, marked by chromosomal condensation & formation of mitotic spindle
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Prometaphase
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Nuclear membrane breaks up, condensation continues
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Metaphase
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Maximal condensation & @ arrangement @ the equatorial plane of the cell
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Anaphase
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Sister chromatids separate
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Telophase
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Chromosomes decondense and nuclear membrane reforms
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Mendel's 1st law
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Segregation of alleles
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Mendel's 2nd law
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Shuffling of genetic material (random assortment)
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