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36 Cards in this Set
- Front
- Back
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Without Sex by single-celled or mulitcellular organisms. the offspring are genetic replicas of the parent
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Asexual Reproduction
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With Sex by multicellualar organismas. requires fertilizatino of an egg by a sperm
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Sexual Reproduction
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What makes up chromosomes?
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DNA & Histone Proteins
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the DNA and protein molecul;es that make up a chromosome
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Chromatin
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The region where the two chromatids are joined together
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Centromere
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the two copies of a chromosome that contain identical genes
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Sister Chromatids
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Microtubules that begin to appear during prophase
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Spindle Fibers
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the process in which the cytoplasm splits after a clevage furrow and two daughter cells form
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Cytokenisis
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The maternal and paternal chromosome pair
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Homolog
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the 2 homologous chromosomes that cross over and line up during prophase
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Tetrads
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the diploid result of fertilzation
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Zygote
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fusion of gametes
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Fertilization
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these are haploid (1n), produced in germ tissue (gonads) via meiosis
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Gametes
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(2n) humans have 46 chromosomes (23 homologous pairs) body cells
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Diploid
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(1n) sperm and egg cells
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Haploid
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tetrads separate and chromosomes move to seperate poles during anaphase
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Disjunction
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a standardized arrangement of a cell showing the pairs within them
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Karyotype
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a non dividing phase, chromosomes appear as chromatin, chromosome duplication occurs
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Interphase
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chromatin become visible short chromosomes, centrosomes/centrioles begin moving towards opposite Ends of the nucleus, spindle fibers(microtubules) begin to appear, nuclear envelope disappears
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Prophase
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chromosomes align along equator of spindle apparatus, spindle fibers attached to the centromere of each Chromosome
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Metaphase
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centromeres of each chromosome divide and chromatids now separate, sister chromatids become Daughter chromosomes, spindle fibers begin to move daughter chromosomes towards opposite poles
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Anaphase
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nuclear envelope reappears around two new daughter nuclei, chromosomes revert to the diffuse Chromatin condition, cytokinesis occurs
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Telophase
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What is the end product of mitosis?
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2 haploid daughter cells identical to mother and to each other, 1 division
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What is the end productin of meiosis?
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4 haploid daughter cells, 2 divisions, it has gametes
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What are three types of asexual reproduction?
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Binary fission- ex. amoebas
Budding- ex. Yeast Vegetative reproduction- ex. Strawberries, Bermuda grass, ferns |
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chromosomes line up with homologs to form tetrads, crossing over occurs between chromatids Of homologous chromosomes, crossing over means chromosomes are different from parent cell’s
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Prophase I
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tetrads align along equator of the cell, spindle fibers attached to centromeres of chromosomes
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Metaphase I
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disjunction- tetrads separate and chromosomes move to opposite poles, here is where the Number of chromosomes are reduced
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Anaphase I
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2 haploid nuclei undergo mitosis to produce 4 haploid daughter cells
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Meiosis II
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occurs in cells of the ovary- oocytes, 4 haploid daughter cell produced, 1 daughter cell develops in a Gamete called ovum (egg), and other 3 become small nonfunctional polar bodies
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Oogenesis
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occurs in testes cells- spermatocytes, 4 haploid daughter cells produces, daughter cells develop into mobile gametes called spermatozoa
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Spermatogensis
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What is the importance of meiosis?
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keeps diploid number constant b/c of haploid gametes -a source of genetic variation
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zygote has an additional chromosome for a homologous pair (2n+1)
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trisomy
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zygote is missing 1 chromosome of a homologous pair (2n-1)
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monosomy
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What process produces a trisomy or a monosomy and what is it?
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Non-disjunction: abnormal separation of chromosomes during meiosis, occurs during anaphase I or II
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Trisomy 21, extra 21st chromosome, most common serious birth defect in US (1 in 700), related to age of Mother, characteristics- mental retardation, heart defects leukemia, short stature, etc.
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Down's Syndrome
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