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Solutions
- -Homogeneous mixtures of two or more pure substances
- - The solute is dispersed uniformly throughout the solvent
- ex. sugar in water
- - Solvent molecules are attracted to the solute molecules
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Dissolution
change in the physical state of a substance
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Saturation
- - A solution of a substance can dissolve no more of that substance (solute) and additional amounts of it will appear
- unsaturated
- saturated
- supersaturated
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Temperature
(Solutions)
Will increase the solubility of a solute in any given solvent
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Osmosis
Net movement of solvent from the area of higer solvent concentration to the area of lower solvent concentration
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Osmotic Pressure
- - Pressure required to stop osmosis
- Positive number: water will go from the cell to the extracellular fluid
- Negative number: water will go from the extracellular fluid to the cell
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Colloids
- - Suspensions of particles larger than individual ions or molecules, but to small to be settled out by gravity
- - Tyndal Effect: Colloidal suspensions can scatter rays of light
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Colloids in Biological Systems
- Aids in the emulsification of fats (lipids) & oils in aqueous solutions
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Chromosome
- - Composed of chromatin & contains the hereditary units, or genes
- - Woven up in histone (associated packing proteins) to form nucleosome
- - Wind & unwind DNA to be able to transcribe
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Karyotype
- - Ordered, visual representation of the chromosomes in a cell
- - Chromosomes arranged by pairs according to their size, shape, & general appearance in mitotic metaphase
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Centromere
Constricted region of a chromosome where sister chromatids are attached to one another and where the chromosome attaches to a spindle fiber
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Allele
- - Genes that can occupy the same gene locus (on different chromosomes)
- - Alternative form of a gene
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Gene
- - A section of a DNA molecule that contains the code for making one polypeptide
- - Unit of heredity existing as alleles on the chromsomes
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Homologues
(Homologous Chromosomes)
- - Similarly constructed chromosomes that have the same shape & contain genes for the same trait
- Look the same
- Control the same traits
- May code for different forms of each trait
- Independent origin- each one was inherited from a different parent
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Gamete
- Haploid sex cell; an oocyte or a sperm that join during fertilization to form a zygote
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Haploid
- - Cell possessing a single copy of each chromosome
- - Half the diploid number; the number of characteristic of gametes that contain only one set of chromosomes
- Human sex cells
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Diploid
- - Cell processing 2 copies/sets of each chromosomes
- - Twice the number of chromosomes found in the gametes
- Human body cells
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Interphase
- - G1: cells undergo majority of growth
- - S: each chromosome replicates (synthesizes) to produce sister chromatids
- Attach at centromere
- Contains attachment site (kinetochore)
- - G2: chromosomes condense & synthesize proteins needed for cell division
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Cell Division
- - Functions: reproduction, growth & development, tissue renewal
- - Part of the cell cycle
- - Interphase
- G1: growth
- S: growth & DNA replication
- G2: growth & final preparations for division
- - 90% of the cell cycle
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Mitosis
- - Type of cell division in which daughter cells receive the exact chromosomal & genetic make up of the parental cell; occurs during growth & repair
- - Produces 2 daughter cells with 46 chromosomes each
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Prophase
(mitosis)
- - Nucleolus has disappeared, and duplicated chromosomes are visible.
- - Chromosomes begin moving apart & spindle is in the process of forming
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Metaphase
(mitosis)
- - Centromeres of duplicated chromosomes are aligned at the metaphase plate (center of fully formed spindle)
- - Centromeric spindle fibers are attached to the sister chromatids come from opposite spindle poles
- - One of the longest stages
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Anaphase
(mitosis)
- - Sister chromatids part & become daughter chromosomes that move toward the spindle poles
- - One of the shortest stages
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Telophase
(mitosis)
- - Daughter cells are forming as nuclear envelopes & nucleoli reappear
- - Chromosomes become less condense
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Cytokinesis
- - Division of the cytoplasm following mitosis & meiosis
- - Animal cells: constriction belt of actin filaments
- - Plant cells: cell wall
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Mitotic Spindle
- - Includes the centrosomes, spindle micro-tubules & the asters
- - Controls chromosome movement during mitosis/meiosis
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Independent Assortment
(meiosis)
- Alleles of unlinked genes segregate independently of each other during meiosis so that the gametes contain all possible combination of alleles
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Crossing-Over
(meiosis)
- - Exchange of corresponding segments of genetic material between non sister chromatids of homologous chromosomes during synapses of meiosis
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Heredity
- Transmission of traits from one generation to the next
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Variation
- Show that offspring differ somewhat in appearance from parents & siblings
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Meiosis
- - Type of nuclear division that occurs as part of sexual reproduction in which the daughter cells receive the haploid number of chromosomes in varied combinations
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Prophase I
(meiosis)
- - Homologous chromosomes come together & line up side by side
- - Exchange genetic material (crossing-over)
- - Form tetrads
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Metaphase I
(meiosis)
- - Homologue chromosomes align at the metaphase plate
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Anaphase I
- - Pairs of homologous chromosomes separate
- - Independent assortment occurs
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Telophase I
(meiosis)
- - Occurs at the end of Meiosis I
- - Form 2 Haploid daughter cells
- - Cytokinesis usually occurs simultaneously
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Interkinesis
(meiosis)
- Period of time between meiosis I & meiosis II during which no DNA replication takes place
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Prophase II
(mieosis)
- - Simliar to prophase I
- - Chromosome start moving to metaphase plate
- - The nuclear envelope breaks down, and the spindle apparatus forms.
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Metaphase II
(meiosis)
- - Chromosomes align at the metaphase plate
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Anaphase II
(meiosis)
- - The centromeres separate, and the two chromatids of each chromosome move to opposite poles on the spindle.
- - The separated chromatids are now called chromosomes in their own right.
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Telophase II
(meiosis)
- - A nuclear envelope forms around each set of chromosomes
- - Cytokinesis takes place, producing four daughter cells (gametes, in animals), each with a haploid set of chromosomes
- - Because of crossing-over, some chromosomes are seen to have recombined segments of the original parental chromosomes.
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Oogenesis
- - Production of oocytes in females by the process of meiosis & maturation
- - Oocyte: Female gamete, or egg prior to fertilization
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Spermatogenesis
- - Production of sperm in males by the process of meiosis & maturation
- - Spermatid: the functional product of meiosis II; becomes sperm
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