Bio 100 - Exam 2
Terms
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- Without Sex by single-celled or mulitcellular organisms. the offspring are genetic replicas of the parent
- Asexual Reproduction
- With Sex by multicellualar organismas. requires fertilizatino of an egg by a sperm
- Sexual Reproduction
- What makes up chromosomes?
- DNA & Histone Proteins
- the DNA and protein molecul;es that make up a chromosome
- Chromatin
- The region where the two chromatids are joined together
- Centromere
- the two copies of a chromosome that contain identical genes
- Sister Chromatids
- Microtubules that begin to appear during prophase
- Spindle Fibers
- the process in which the cytoplasm splits after a clevage furrow and two daughter cells form
- Cytokenisis
- The maternal and paternal chromosome pair
- Homolog
- the 2 homologous chromosomes that cross over and line up during prophase
- Tetrads
- the diploid result of fertilzation
- Zygote
- fusion of gametes
- Fertilization
- these are haploid (1n), produced in germ tissue (gonads) via meiosis
- Gametes
- (2n) humans have 46 chromosomes (23 homologous pairs) body cells
- Diploid
- (1n) sperm and egg cells
- Haploid
- tetrads separate and chromosomes move to seperate poles during anaphase
- Disjunction
- a standardized arrangement of a cell showing the pairs within them
- Karyotype
- a non dividing phase, chromosomes appear as chromatin, chromosome duplication occurs
- Interphase
- chromatin become visible short chromosomes, centrosomes/centrioles begin moving towards opposite Ends of the nucleus, spindle fibers(microtubules) begin to appear, nuclear envelope disappears
- Prophase
- chromosomes align along equator of spindle apparatus, spindle fibers attached to the centromere of each Chromosome
- Metaphase
- centromeres of each chromosome divide and chromatids now separate, sister chromatids become Daughter chromosomes, spindle fibers begin to move daughter chromosomes towards opposite poles
- Anaphase
- nuclear envelope reappears around two new daughter nuclei, chromosomes revert to the diffuse Chromatin condition, cytokinesis occurs
- Telophase
- What is the end product of mitosis?
- 2 haploid daughter cells identical to mother and to each other, 1 division
- What is the end productin of meiosis?
- 4 haploid daughter cells, 2 divisions, it has gametes
- 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 - 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
- Prophase I
- tetrads align along equator of the cell, spindle fibers attached to centromeres of chromosomes
- Metaphase I
- disjunction- tetrads separate and chromosomes move to opposite poles, here is where the Number of chromosomes are reduced
- Anaphase I
- 2 haploid nuclei undergo mitosis to produce 4 haploid daughter cells
- Meiosis II
- 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
- Oogenesis
- occurs in testes cells- spermatocytes, 4 haploid daughter cells produces, daughter cells develop into mobile gametes called spermatozoa
- Spermatogensis
- What is the importance of meiosis?
- keeps diploid number constant b/c of haploid gametes -a source of genetic variation
- zygote has an additional chromosome for a homologous pair (2n+1)
- trisomy
- zygote is missing 1 chromosome of a homologous pair (2n-1)
- monosomy
- What process produces a trisomy or a monosomy and what is it?
- Non-disjunction: abnormal separation of chromosomes during meiosis, occurs during anaphase I or II
- 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.
- Down's Syndrome