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58 Cards in this Set
- Front
- Back
What is Cell reproduction
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Creation of new cells from already existing ones
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Chromatin
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All the DNA molecules plus their associated protein in the nucleus
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Chromosomes
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An individual DNA molecule plus its associated protein
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How many Chromosomes in a human and how many Pairs?
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46 Chromosomes in a human
23 pairs |
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Homologous chromosomes:
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Two members of a pair of chromosomes that are similar in size and shape and that carry the same genes
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Karyotype
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A picture of your chromosomes
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What does The last pair of chromosomes do?
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Determines the sex
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What are genes?
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Unites of instructions that influence a partcular trait
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What is a Locus
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Location of a gene on a chromosome
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What are Alleles?
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Alternative forms of a gene
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What is a Dominant Allele
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One allele of a pair that suppresses the effect of the other allele in the pair
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What is a Recessive Allele
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The allele in the pair that is suppressed
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What is Homozygous
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If the two alleles are in a pair are the same
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What is heterozygous
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The two alleles are in a pair are different
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What is Genotype
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Genetic makeup of an individual
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What is Homozygous dominant individual
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has two dominant alleles for the trait being studied
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Homozygous recessive individual
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has two recessive alleles for the trait being studied
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Heterozygous individual
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has two different alleles
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What is Phenotype
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external manifestation (expression) of the gene
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Diploid Cells
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Has two chromosomes of each type
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What are haploid cells
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Have only one chromosome of each type
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Describe germ cells
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Cells that produce gametes (diploid) ovary cell – 46 and testis cell - 46
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What are Gametes
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egg and sperm (sex cells)
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What is chromatin made of?
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DNA + Proteins
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Nucleosomes
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are bead like structures formed of DNA wound around 8 proteins
----o-----o-----o-----o---- |
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DNA duplicates
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(46) -> (92)< (46) & (46)
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Sister Chromatids
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the two parts of a chromosome just before cell division. (Remain attached at the centromere)
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What is the cell cycle?
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Comprises all the events in the lifetime of a cell, from the time it is produced to the time it completes division itself.
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4 Main Events in the lifetime of a Cell
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Growth
Duplication of DNA Nuclear Division Cytoplasmic Division |
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What can the cell cycle be divided into?
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Interphase and Mitosis
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Events in Interphase
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G1 phase, S phase and G2 phase
G1: The first gap (resting stage) S phase: Synthesis phase (replication of DNA phase) G2 phase: 2nd gap interval (resting stage) |
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IPMATC
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Prophase, Metaphase, Anaphase, Telophase, and Cytokinesis
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5 Events in Prophase
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In the nucleus
-Nucleolus disappears -Nuclear membrane starts disintegrating -chromosomes shorten and condenses In the cytoplasm -Spindle fibers are formed -Centrioles duplicate |
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Events in Metaphase?
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- Nuclear membrane completely disappears
- Spindle fibers attach to centromeres of chromosomes - And they pull on them until they are oriented in the equatorial region of the cell |
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Events in Anaphase?
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-Spindle fibers start pulling sis chromatids to the opposite poles
-Sister chromatids are pulled apart which they are then called chromosomes |
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Events in Telophase?
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-Chromosomes arrive at poles
-Return to being thread-like - Nuclear membrane and nucleolus reappear |
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Cytokinesis?
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Cytoplasm divides after nucleuos
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Cytokinesis in Plant Cells
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Vesicles containing (come) from Golgi complex cell wall material get lined up at the equator combining to make a cell plate then a new cell wall is formed to parent cells.
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Cytokenis in Animal Cells
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The formation of cleavage furrow which (then divides the cell) which divides from the contracting ring of microfilaments at the equator that get aligned
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What happens in Meiosis?
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Leads to gamete formation (sperm and egg)
Diploid germ cells –meiosis Haploid gametes *Reduced to half* Germ cells undergo meiosis gets 4 daughter cells |
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What does meisois have that mitosis does not have?
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Synapsis (they look for their partner and pair homologous chromosomes) and then crossing over take place (Non sister chromatids cross over and exchange genes and chromosomal segments in Propahse 1
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What is Mitosis for?
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Growth and repair and Asexual reproduction
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What is Meiosis for?
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Gamete formation
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End result: (# of daughter cells produced) in Mitosis
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2 diploid daughter cells
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End result: (# of daughter cells produced)
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4 haploid daughter cells
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Chromosome #: in Mitosis when finished
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Maintaining from generation to generation
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Chromosome #: in Meiosis when finished
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halved
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What is Variation in a species brought about by?
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a. Independent assortment of Chromosomes
b. Random Fertilization c. Crossing over |
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What is Independent assortment of Chromosomes
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random segregation (separation) and assortment (packaging) of chromosomes during gamete formation (gametogenesis) to produce unique gametes.
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What is random fertilization?
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-Any one of the 8 million eggs can unite with any one of the 8 million sperms out there
- Hence, you could get a zygote that could have any one of the 64 trillion possible combinations of chromosomes (8x10*6 X 8x10*6 = 64X10*24) |
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What is Crossing Over?
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-The exchange of chromosomal segments between non sister chromatids of homologous chromosomes in Prophase 1
-Gametes formed get random mixes of paternal and maternal chromosomes -This gametes formed are different (varied), resulting in variation in the population |
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What are some errors in meiosis?
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Non-disjunction, Trisomy 21
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What is Non-disjunction?
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-Sis chromatids do not disjunct causing gametes formed to have one less or one more than the normal number of chromosomes it should have
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What is Trisomy 21
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When women produces (n+1) egg, the extra chromosome being chromosome #21
Thus zygote formed has 3 copies of #21 (47 chromosomess). This is also called Downs syndrome. |
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What is Turner Syndrome
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-Females that are short, infertile because no functional ovaries
Lack One X chromosome (45 Chromosome) |
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What is Klinefelter syndrome
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- XXY
-Taller than average -Testes abnormally small and do not produce sperm - Gynecomastia (partial breast development) |
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What is XYY condition (Jacobs Syndrome)
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-Males
-Taller than average - Mildly retarded - Gets into a lot of trouble |
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What is XXX condition?
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- Slightly lower IQ
-Females -Emotional behavioral problems - Females with triple X syndrome have normal sexual development and are to conceive children. |