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103 Cards in this Set
- Front
- Back
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Multicellular organisms depend on cell division for |
Development from fertilized cells Growth Repair |
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Genome |
All Dna in a cell |
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Chromosomes |
Dna tightly packed in a cell |
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Somatic cells |
Non reproductive cells with two sets of chromosomes, diploid |
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Gamete |
Reproductive cells (sperm and egg) Have half as many chromosomes as somatic, haploid |
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Chromatin |
Eukaryotic chromosomes consisted of this... Complex of Dna and protein that condenses during cell division |
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Sister chromatids |
Each duplicated chromosome has this...These separate during cell division |
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centromere
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is the narrow "waist" of the duplicated chromosome, where the two chromatids are most closely attached
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Mitosis,
Cytokinesis |
the division of the nucleus
the division of the cytoplasm |
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Meiosis
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yields nonidentical daughter cells that have only one set of chromosomes, half as many as the parent cell (produces gametes)
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The cell cycle consists
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Mitotic (M) phase (mitosis and cytokinesis) Interphase(cell growth and copying of chromosomes in preparation for cell division)
Interphase (about 90% of the cell cycle) can be divided into subphases: G1 phase (first gap) S phase (synthesis) G2 phase (second gap) |
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Prophase
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Chromosomes are condensing |
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Prometaphase |
Chromosomes apparent, nuclear envelope fragments |
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Metaphase |
Spindle complete, chromosomes attach to microtubles, chromosomes aligned along metaphase plate |
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Anaphase |
sister chromatids seperate |
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Telophase |
daughter nuclei form(Cytokinesis is well underway late in this phase) |
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centrosome
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the microtubule organizing center of the cell
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An aster
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(a radial array of short microtubules) extends from each centrosome
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kinetochores
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During prometaphase, some spindle microtubules attach to the _______ of chromosomes and begin to move the chromosomes
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metaphase plate
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chromosomes are all lined up at the this, the midway point between the spindle’s two poles.
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Nonkinetochore |
microtubules from opposite poles overlap and push against each other, elongating the cell |
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a cleavage furrow in animal cell and a cell plate in plant cells
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forms during cytokinesis
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binary fission
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Prokaryotes (bacteria and archaea) reproduce by a type of cell division
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origin of replication
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In binary fission, the chromosome replicates beginning here
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cell cycle control system
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The sequential events of the cell cycle are directed by a distinct _________, which is similar to a clock,
which has specific Checkpoints where the cell cycle stops until a go-ahead signal is received. |
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G0 (Gzero) phase
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If the cell does not receive the go-ahead signal, it will exit the cycle, switching into a nondividing state.
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cyclins and
cyclin-dependent kinases (Cdks) |
Two types of regulatory proteins are involved in cell cycle control
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MPF (maturation-promoting factor)
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is a cyclin-Cdk complex that triggers a cell’s passage past the G2 checkpoint into the M phase
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growth factors, external signals
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proteins released by certain cells that stimulate other cells to divide
For example, platelet-derived growth factor (PDGF) stimulates the division of human fibroblast cells in culture |
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internal signal
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An example is that kinetochores not attached to spindle microtubules send a molecular signal that delays anaphase
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density-dependent inhibition
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Another example of external signals in which crowded cells stop dividing
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anchorage dependence
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Most animal cells also exhibit this, in which they must be attached to a substratum in order to divide
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transformation
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A normal cell is converted to a cancerous cell.
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benign tumor
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If abnormal cells remain at the original site,
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Malignant tumors
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invade surrounding tissues and can
metastasize, exporting cancer cells to other parts of the body, where they may form secondary tumors |
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heredity
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Traits are passed from one generation to the next
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variation
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the offspring differ in appearance.
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Genetics
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study of heredity and variation
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locus
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On each chromosome, a genes location
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number of chromosomes in human
somatic cells and gamete |
46 homologous chromosomes (23 pairs)
23 haploid |
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histones
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DNA are organized into chromosomes, wrapped around these
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traits
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The gene is the heredity units that passes from parent to offspring
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Asexual reproduction
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single individual passes copies of it genes This leads to an identical copy of the parent (clone),
difference can only arise through mutations |
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Sexual reproduction
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two parents give rise to an offspring There is a combination of genes from both parents
This leads to variation in the offspring |
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Pairs 1 – 22
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are autosomes
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23rd pair
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is sex chromosome
Y chromosome is much smaller and doesn’t carry as many genes as the X The Y chromosomes has unique genes which are not found on the X |
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zygote
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the result of The union of sperm and egg, and the fusion of their nuclei = fertilization
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Ovaries give rise to Testis give rise to
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oocyte (egg) spermatocyte (sperm)
and are only made through meiosis |
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Alteration of generations |
In most plants (some algae) Both diploid and haploid multicellular stages Spores divide to produces a second multicellular haploid gametophyte |
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In most fungi (some protists) |
Gametes fuse to form a diploid zygote Zygote does not develop (stays single cell) but produces haploid cells (spores) by meiosis These spores grow into multicellular organisms which produce gametes |
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Mitosis Vs. Meiosis
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Mitosis 1 division 2 diploid daughter cells
Synapsis does not occur Meiosis 2 divisions 4 haploid daughter cells Synapse of homologous chromosomes occurs at prophase I, forming tetrads |
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Three mechanisms are responsible for variation arising from sexual reproduction
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Independent assortment Crossing over
Random fertilization |
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Independent Assortment
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Maternal or paternal set of chromosomes can be oriented on either side 50% chance a daughter cell will get maternal or paternal chromosome
Each homologous pair is positioned independently of the others |
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The number of different possibilities when chromosomes sort is
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2 to the power of the haploid number
2 to the 23rd resulting in 8.4 million combinations |
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Crossing Over
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During prophase I, homologous chromosomes line up They become physically connected by a protein structure, (process called synapsis)
Genetic rearrangement can occur between non–sister chromatids |
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Random Fertilization |
A single male sperm fertilizes a single female egg There are 8 millions possible combination due to independent assortment per gamete |
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Significance of Variation Natural Selection |
The individuals best suited for the local environment leave the most offspring, passing along these traits. As the environment changes, individuals best suited to cope with these changes leave the most offspring, passing along these traits. |
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heredity
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Traits are passed from one generation to the next
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variation
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the offspring differ in appearance.
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Genetics
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study of heredity and variation
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locus
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On each chromosome, a genes location
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number of chromosomes in human
somatic cells and gamete |
46 homologous chromosomes (23 pairs)
23 haploid |
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histones
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DNA are organized into chromosomes, wrapped around these
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traits
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The gene is the heredity units that passes from parent to offspring
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Asexual reproduction
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single individual passes copies of it genes This leads to an identical copy of the parent (clone),
difference can only arise through mutations |
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Sexual reproduction
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two parents give rise to an offspring There is a combination of genes from both parents
This leads to variation in the offspring |
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Pairs 1 – 22
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are autosomes
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23rd pair
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is sex chromosome
Y chromosome is much smaller and doesn’t carry as many genes as the X The Y chromosomes has unique genes which are not found on the X |
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zygote
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the result of The union of sperm and egg, and the fusion of their nuclei = fertilization
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Ovaries give rise to Testis give rise to
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oocyte (egg) spermatocyte (sperm)
and are only made through meiosis |
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Alteration of generations
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In most plants (some algae) Both diploid and haploid multicellular stages
Sporophyte (diploid) produces spores (haploid) Spores divide to produces a second multicellular haploid gametophyte Gametophyte produces gametes, leading to fertilization |
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In most fungi (some protists)
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Gametes fuse to form a diploid zygote Zygote does not develop (stays single cell) but produces haploid cells (spores) by meiosis These spores grow into multicellular organisms which produce gametes
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Mitosis Vs. Meiosis
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Mitosis 1 division 2 diploid daughter cells
Synapsis does not occur Meiosis 2 divisions 4 haploid daughter cells Synapse of homologous chromosomes occurs at prophase I, forming tetrads |
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Three mechanisms are responsible for variation arising from sexual reproduction
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Independent assortment Crossing over
Random fertilization |
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Independent Assortment |
Maternal or paternal set of chromosomes can be oriented on either side 50% chance a daughter cell will get maternal or paternal chromosome |
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The number of different possibilities when chromosomes sort is
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2 to the power of the haploid number
2 to the 23rd resulting in 8.4 million combinations |
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Crossing Over
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During prophase I, homologous chromosomes line up They become physically connected by a protein structure, (process called synapsis)
Genetic rearrangement can occur between non–sister chromatids |
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Random Fertilization
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A single male sperm fertilizes a single female egg There are 8 millions possible combination due to independent assortment per gamete
8 million sperm combinations * 8 million egg combinations = over 64 trillion diploid (zygote) possibilities |
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Significance of Variation Natural Selection
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The individuals best suited for the local environment leave the most offspring, passing along these traits. As the environment changes, individuals best suited to cope with these changes leave the most offspring, passing along these traits.
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Blending Hypothesis
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Genetic material from parents mix to provide traits Does this work? This would eventually lead to uniformity All traits would eventually blend and become diluted
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Particulate Hypothesis: |
Parents pass on genes that create offspring identity Genes can be sorted and passed generation after generation without becoming dilute |
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true–breeding =
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self pollinated plants, all offspring are same variety as parent
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P generation = F1 =
F2 = |
–parental generation–first filial generation (filial is Latin for son)
–second filial generation resulting from self pollination |
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mendel's ratio of homozygous |
dominant crossed with homozygous recessive. Both heterozygous offspring is 3 to 1 |
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allele
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The alternate versions of a gene
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homozygous
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Identical alleles for a gene
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heterozygous
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Different alleles for a gene
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Phenotype
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is expressed traits (physical appearance)
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Genotype
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is genetic makeup
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test cross
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Crossing an organism with an unknown genotype that has a dominate phenotype with a homozygous recessive organism
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monohybrid cross
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Crossing plants looking at one trait (e.g. flower color)
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dihybrids
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Crossing and following two traits
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dihybrid cross ratio
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9 to 3 to 3 to 1
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Law of independent assortment
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states each pair of alleles segregate independently of other pairs of alleles during gamete formation
* This only applies to genes on different chromosomes, genes on the same chromosome would be inherited together |
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Codominance
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is when two alleles both affect the phenotype in separate ways (two phenotypes are present together).
e.g. blood type A and B being codominant |
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Incomplete dominance
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is when the offspring have phenotypes somewhere between the parental phenotypes (a blending of traits occurs)
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Pleiotropy
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is when a gene has multiple phenotypic effects (this is most genes actually)
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Epistasis
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Greek for stopping....a gene at one location alters the phenotypic expression of a gene at a second location
e.g. mice being black(B) or recessive brown(b) and another trait if the pigment is expressed (C) otherwise the mouse is albino |
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Polygenic Inheritance
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The additive effect of two or more genes on a single phenotypic character (skin color, height, etc).
The character vary in the population along a continuum = quantitative characters |
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Genotypes may have norm of reaction
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which is a range of phenotypic possibilities
which can be altered by both genetic and environmental influences are called multifactorial |
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Pedigree Analysis
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the known family history of particular traits to assemble a tree to understand the trend through the family
Males are represented by squares Females are represented by circles Horizontal lines between male and female represent mating Shaded circle and squares represents the trait being traced |
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Fetal Testing |
Amniocentesis = a needle inserted into the uterus extracts 10 ml of amniotic fluid Some tests can be run on chemicals in the fluid itself to show genetic disorders Cells from the fluid can also be cultured for karyotyping to identify chromosomal defects Karyotyping can be done immediately to test for chromosomal abnormalities |
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Imaging techniques can be used to determine anatomical abnormalities
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Ultrasound fetoscopy
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