STR : variable DNA, unique patterns, identifiable
PCR : polymerase chain reaction
23 pairs of chromosomes
Cell Cycle
G1: growth
S: DNA synthesis
G2: preparation for cell division
M: mitosis -- nuclear division
Cytokinesis: cell division
G2 : chromosomes are composed of sister chromatids in this stage of the cell cycle
Mitosis
Prophase: chromosomes condense, become visible, nuclear membrane disintegrates
Metaphase: chromosomes line up on metaphase plate
Anaphase: sister chromatids separate
Telophase: chromosomes decondense, 2 nuclear membrane form
G1 phase prior to meiosis
diploid cell: chromosome replicate at S phase and condense at start of meiosis
Meiosis 1: homologous chromosomes separate
Meiosis 2: sister chromatids separate; 4 cells with individual chromosomes
Meiosis 1
Prophase 1:
chromosomes condense, become visible, nuclear membrane starts to disintegrate, homologous chromosomes pair up (synapse). Crossing over: reciprocal exchanges of DNA from sister chromatids in a homologous pair
Metaphase 1:
chromosomes line up on metaphase plate, IN PAIRS
Anaphase 1:
chromosomes separate from their homologous half pair
Telophase 1:
chromosomes decondense, 2 new nuclear membrane forms
Cytokinesis:
cell division; 2 cells
Meiosis 2:
Prophase 2:
chromosomes condenses, become visible, nuclear membrane disintegrates
Metaphase 2:
chromosomes line up on metaphase plate
Anaphase 2: sister chromatids separate
Telophase 2: chromosomes decondense, nuclear membrane forms
Cytokinesis: cell division; 4 cells
Diploid number: number of chromosomes when they are in pairs; our somatic (body) cells are diploid
Haploid number: half number of diploid cells in our gametes (Sex cells)
Non-Disjunction Error in Meiosis: uneven distribution of chromosomes during anaphase
Independent Assortment: occurs in meiosis 1
For n Pair of chromosomes: 2^n number of possible different gametes
Mendelian Principle 1
Dominance
controlling element for one variant dominates the other variant in the Hybrid F1
Mendelian Principle 2
Segregation
in gametogenesis (formation of sex cells) variants of genes (alleles), segregate to different gametes
Homozygous: alleles same eg. TT, tt
Heterozygous: alleles different eg. Tt
Mendelian Patterns:
Dominance eg. TT x tt
Segregation eg. Tt x Tt
Independent Assortment
Non-Mendelian Patterns
Gene linkage
CO-Dominance/Incomplete Dominance
Red (CrCr) x Pink (CrCw)
Karyotype
a photographic representation of the chromosomes
reveals the number, size, and form of chromosomes found within an actively dividing cell
Animal Cells: Cleavage furrow
in animal cells, cytokinesis involves the formation of a cleavage furrow, which constricts like a drawstring to separate the cells
Plant Cells: Cell plate
in plant cells, cytokinesis is when vesicles from the Golgi apparatus move along microtubules to the center of the cell and coalesce to form a cell plate, which then forms a cell wall between the two daughter cells
Epistasis
Greek ephistanai, meaning stopping
in some gene interactions, the alleles of one gene mask the expression of the alleles of another gene
Polygenic
quantitative traits usually
means that multiple genes contribute to the outcome of the trait
Linkage: when two genes are close together on the same chromosome, they tend to be transmitted as a unit
Genetic Mapping
the study of the arrangement of genes in a species genome
Genetic Map: the linear order of genes along a chromosome is shown in a chart
Genetic Engineering: direct manipulation of genes for practical applications
Plasmids: small, circular pieces of DNA that are found naturally in many strains of bacteria and exist independently of the bacterial chromosome
Restriction Enzymes
to cut DNA
restriction endonucleases
protect bacterial cells from invasion by viruses by degrading the viral DNA into small fragments
DNA fingerprinting: technology for identifying and distinguishing among individuals based on variation in their DNA
STR
short tandem repeat sequences
short DNA sequences that are repeated many times in a row
amplified when PCR is used for DNA fingerprinting
PCR
polymerase chain reaction
another technique to copy DNA without the aid of vectors and host cells is process called PCR
goal of PCR: to make many copies of DNA in a defined region, perhaps encompassing a gene or part of a gene
Incomplete Dominance: a heterozygote that carries two different alleles exhibits a phenotype that is intermediate between the corresponding homozygous individuals
Co-Dominance: a single individual expresses two alleles eg. IAIB -- type AB
Multiple Alleles: although diploid individuals have only two copies of most genes, the majority of genes have three or more variants in natural populations
Chromosomes replicate during interphase
Genes that are linked do not assort independently during meiosis
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