Biotech Module 3 PDF

Cell Cycle ❖ Cancer is a result of Sequence of events throughout a uncontrolled cell division typical cell’s life ❖ Aging is also a factor ❖ Euka...

Cell Cycle ❖ Cancer is a result of Sequence of events throughout a uncontrolled cell division typical cell’s life ❖ Aging is also a factor ❖ Eukaryotic cells have two types: somatic and sex cells Eukaryotic Cell Division ❖ Somatic: body cells [growth Two types: mitosis and meiosis and repair] ❖ Sex cells - gametes Ploidy Somatic cell cycle has two stages Number of sets of chromosomes in a ❖ Interphase - not part of cell mitotic proper but it prepares ❖ Haploid (n) - one set the cell for mitotic division ❖ Diploid (2n) - two complete - The cell grows haploid sets of chromosomes performs metabolic Our somatic cells have diploid set (46) functions, and copies Gamete cells contain haploid (23) - we the DNA get the other set from the other - Like in prokaryotic, parent before it divides by either binary fission or Mitosis budding, it prepares Comes from the Greek word “mito” first (DNA protein x2) meaning thread - due to the ❖ Mitotic phase - once DNA is thread-like appearance of condensed copied, the cell starts to divide chromosomes its nuclear [mitosis] and ❖ When cells are not dividing - cytoplasmic material chromosomes uncondensed [cytokinesis] Various stages of nuclear division ❖ The whole process generates IPMATC - interphase is not part of two daughter cells that are mitotic identical to the parent cell, it would produce aberration if Cell’s resting face/dormant - they thought not there was no metabolic activity but they Cell cycle is different from cell division found out that this is where growth and DNA ❖ Cell cycle - everything that replication happens goes on or the life cycle. From the moment it was produced through meiosis or mitosis until cell death Essential for the growth of the organism, the replacement of damaged cells, regeneration of cells Has to be regulated because you’ll get cancer if not [neoplasms}  - Protein increases - Mitochondria and ribosomes increase in size ❖ S - DNA synthesis/replication takes place ❖ G2 - coiling and condensation of chromosomes start Takes up 90% of the process G1 and G2 provide cells more time to grow Mitotic phase The culmination of the cell cycle Include various stages of nuclear division (mitosis) ❖ Mitosis - division of the nucleus so that each daughter cell is identical to the parents (clone) DNA Chromosomes are composed of DNA wrapped around the protein histones Chromosomes will wind until it become condensed Proteins act as a pool where DNA winds Interphase Histone + DNA = nucleosome Divided into three stages: Each chromosome replicates before ❖ G1 - high metabolic activity mitosis  ❖ DNA synthesis may take place 4n during interphase No breaks just smooth transitions in between Mitosis At the start of mitosis, chromosomes become compact Kinetochore - where spindle fibers adhere/attach when you need to divide chromosomes Centromere - holds two sister chromatids together. Just to keep the “x” intact Chromatid - replication of a chromosome Metaphase Chromatin - genetic material that Chromosomes aligned at the turns to chromatid when replicated metaphase plate (middle) governed by the spindle fibers Interphase Spindle fibers attached to the The time span between cytokinesis kinetochores and mitosis Centrosomes move to opposite poles The cell grows as it continues to Chromosomes will move to the synthesize or replicate DNA and middle proteins that are necessary for the Kinetochore proteins digest the next cell division spindle fibers Chromosomes start duplicating 4n Since DNA is replicated, we started with 2n and will become 4n as the cell divided Deceptively uneventful The cell grows in size Prophase Chromatins condense forming chromosomes Outside the nucleus, spindle fibers assemble and form (microtubules) Spindle fibers will attach to the chromosomes so they will separate Anaphase The disappearance of nuclear Briefest phase membrane (disintegration) Paired chromosomes separate at the The nucleolus will also disappear kinetochore and will move to the Centrosomes will move to opposite opposite side of the pole poles of the cell Microtubules pull the kinetochore  Centromeres will eventually divide Spindle fiber dispersed and separate the two sister The mitotic phase is over but not the chromatids cell division When they divide, they become separate chromosomal entities ❖ The one contained by daughter cells Ends when daughter chromosomes have reached their respective poles 4n Cytokinesis Cytoplasmic division Cytoplasm of the cell is physically divided to house newly formed daughter cells There will be formation of divider in the cell Separate to form two daughter cells Cell division is complete when the infolding edges of cytoplasm meet and fuse Will fold inwards and meet in the middle then separate Telophase Spindle fiber disassembles The nuclear membrane and nucleolus reappear Cleavage furrows are formed Expanding cell plate if a plant cell, cleavage furrow if an animal Expand and infolding to prepare for cytokinesis Cell Cycle checkpoints Chromosomes return to their The cell cycle must be tightly uncondensed form regulated  Each checkpoint is controlled by correctly attached to microtubules at enzymes and ensures the fidelity and metaphase template. All chromatids integrity of copied DNA sequences are attached to spindle fiber before If errors are detected, the cycle will be they proceed to anaphase or before put on hold they separate. Otherwise you might Repair mechanisms are initiated get cells with either less or more When damage is too severe, the cell chromosomes will just undergo programmed cell death or apoptosis If an error is allowed to go on, the cell continues to divide and produce more mutations or erratic cell growth - where cancer starts Error left unchecked may result to uncontrolled growth - neoplasm (cancer) Cancer neoplasm Checkpoints are bypassed Each successive round of unchecked cell division produces more damaged daughter cells Cancer in the human body can divide much more frequent Has telomerase - enzyme expressed, Cell Major Checkpoints repairs wear and tear at the ends of G1 - first; where cell size increases chromosomes caused by cell division and is evaluated (energy levels, Cells age - so they are wear and tear nutrients), and other external factors Telomerase prevent this so they - If there’s inadequacy, the cell continue to develop will not continue to the S phase, DNA will not synthesize Meiosis G2 - further grow in size, ensure all Sexual reproduction DNA has been replicated and not Reduction in the number of damaged. If there is damage and chromosomes cannot be prepared then cell death Primary basis for variation in M - spindle checkpoint - cell ensures organisms that all your sister chromatids are  2 rounds of nuclear division with one Chromosomes coiled and aligned in round of DNA replication homologous pairs Production of gametes Nuclear envelope and nucleolus Involves mixing of genetic materials disintegrate ❖ Zygote - first cell of individual Ploidy 2n Cytokinesis - happens after phase 1 Where homologous pairs formed Four resulting cells - rarely identical Crossing over: genes are shuffled Interphase 2n to tetrads (eggs and Homologous chromosome - chiasma - sperms) recombinant chromatid Chiasma - site of Crossing over Meiosis I ❖ For variation, produce Chromosome number is reduced to offspring that are not exactly half identical (to not produce Reduction division clones) Interphase I ❖ Support variation (strong vs Starts with diploid 2n weak genes) Duplication of genetic material Exchange of genetic material Chromosomes condensed Synapsis - the events 46 chromosomes (23 from each Bi-valent: pairing of 2 homologous parent) chromosomes Homologous pairs: finding same 2 chromosomes and 4 chromatids fromeach parent: paired to form One chromosome coming originally tetrads (XX or XY) from each parent Four tetrads Homologous Chromosomes - members of each pair of chromosomes have identical: ❖ DNA length, Amount of DNA ❖ Genes present and centromeres in the precise loc Metaphase I Tetrads align on the midplane Both sister kinetochores of one duplicate dchromosome are attached by the spindle fibers to the same pole Ploidy: 2n Prophase I  Meiosis II Chromosome number is not halved Equational division No interphase No DNA replication Prophase II Similar to mitotic No crossing over Anaphase I DNA is not replicated Chiasmata separate Ploidy: n Each pole receives a random Starts with 2 cells combination of maternal and paternal No pairing of homologous chromosomes chromosomes Only one member of each homologus pair present at each pole Ploidy: 2n Metaphase II Alignment of chromosomes at metaphase plate Telophase I Only completed when 2 cells have been formed No new nuclear membrane form Nucleolus may appear Ploidy: n There can be cleavage Each nucleu will have a haploid no. Anaphase II Centromeres divide Sister chromatids separate Ploidy n Telophase II + Cytokinesis Complete cell division Results into 4 cells Ploidy: n One representative for each homologous pair at each pole Each is unduplicated chromosome (single) There is no DNA replication between two divisions Start with 1 cell ends with 4 cells 3 egg cells will give rise to offspring Genetic Disorders Occurs when there is a nondisjunction of the chromosomes ❖ Homologous chromosomes do not separate in Meiosis I ❖ Sister chromatids do not separate in Meiosis II Chromosomal mutations ❖ Changes in chromosome number (polyloidy, monosomy, trisomy) ❖ Changes in chromosome structure Mutation increases genetic variation  Mutation can happen in prokaryotic Characterized by: flat face, broad cell because of fast process, which nose, large tongue, upward-slanting results n diversity in species eyes No separation of tetrads (p1) Has same genetic abnormalities - ❖ Results in less or more same features, heart problems daughter cells 50 max age - extra cells come from Polyploidy mom More than 2n Chromosome 13 - also a trisomy ❖ Triploidy (3n) ❖ Tetraploidy (4n) ❖ Pentaploidy (5n) Common in plants, rare in animals Arises following hybridization Results to an odd number od chromosome; infertile - no even pairing - mutaiion Monosomy and Trisomy Moonosomy - 2n-1 Trisomy - 2n+1 Results from the nondisjunction of chromosomes ❖ Meiosis I - both members of a Klinefelter Syndrome homologous pair are Mostly infertile contained in one daughter cell Also known as 47, XXY ❖ Meiosis II - sister chromatids 2 X chromosomes, 1 Y fail to separate Considered male ❖ Can also result to the changes in sex chromosome number Trisomic individual more likely to survive than a monosomic One daughter cell can have manay duplicate if tetrads do not separate ❖ You can have daughter cells that dont produce something ❖ Lack of chromosomes or more Happens more in older women ❖ If mother conceive beyon 25 y/o (cells also age) or unhealthy habits Down’s Syndrome Also known as trisomy 21 Turner syndrome Rarely passed on Also known as XO Matinis voice No Y chromosome Can live long Develop as females Female - period and uterus is not fully developed 0, 1, 2, 3, 4, 5, 6, 7, 8, and 9 () Heredity Passing of characteristics or traits from parents to offspring Genetics Study of heredity Loci - locations on the chromosome Jacobs Syndrome where a gene appears. The Also known as 47, XXY coordinates of a particular gene on a Nondisjunction during chromosome Allele - different versions of genes. Ex: blood type - 3 alleles Meiosis - there are maternal and paternal; counterparts of our gene ex: breast cancer (history) Gregor Mendel - father of heredity ❖ Study of pea plants ❖ Establish mendelian genetics ❖ Principles of heredity ❖ Austrian Monk ❖ Inspired by biologist Frank Onger - inheritance Peal Plant Pisum sativum Cri-du-chat syndrome Capable of self-fertilization Caused by deletion of short arm of Pollen of one plant germinate with its chromosome 5 stigma Abnormal larynx development  Pollen germinates within the female partner allele is identical or sexual part of the plant different Mendel removed the male stamen Ex: RR, Rr - smooth before pollen matured and then he ❖ Recessive allele - fails to cross-pollinated that with another express its phenotype when plant to produce certain characteristic dominant allele is present he wanted to see Ex: rr - wrinkled Mendel’s Third Postulate Segragation - during the formation of Trat Dominant Rcessive gametes, the paired unit factors Flower Color Purple White separate or segregate randomly so that each gamete receives one or the F. position axial terminal other with equal likelihood. Seed color yellow green RR x rr - gamete formation where R and r are the gametes Seed shape round wrinkled Modern Genetic Terminilogies Pod shape inflated constricted Phenotype - refers to physical Pod color green yellow appearance or characteristics of an organism. Combination of genotype Stem length Tall dward Genotype - refers to the genetic composition of an organism Mendel’s First Postulate Homozygous - gene pair where Unit factors occurs in pairs ex: purple maternal and paternal genes are and white identical Postulate - idea that is suggested or ❖ Homozygous dominant - RR accepted as basic principle before ❖ Homozygous recessive - rr further idea is formed or developed. Heterozygous - gene pair where Gives rise to further studies material and paternal genes are Hypothesis - can still be tested different Unit Pairs: Smooth - RR; ROugh - rr ❖ Heterozygous - Rr Monohybrid Cross - a cross between Mendel’s Second Postulate contrasting characteristics of a single Dominance/Revessiveness trait When two unlike unit factors Mendel interpreted his results as responsible for a single character are various traits are controlled by pairs present in a single individual, one unit of factors, one factor from the male factor is dominant to the other, which parent and another from the female is said to be recessive parents ❖ Dominant allele - produce the Dihybrid Cross - use 2 different traits same phenotype whether its Naming alleles  Use the first letter of the recessive ❖ Principles of segregation - two trait members of a gene pair Uppercase for dominant segregate from each other in Lowercase for recessive the formation of gametes ❖ Half the gametes carry one DNA allele and the other half carry Chains of nucleotides the others allele Base chains Made up of base pairs Mendel’s fourth postulate Bacteriopahage - virus that infects a Independent assortment - genes for bacteria different traits assort independently Chromosomes wind up in a pool to be of one another in gamete formation condensed (mixing and matching of male gametes with female gametes). Basis of inheritance: CHROMOSOMES Different genes are inherited Genes are located in the chromosomes separately Behavior of chromosomes during meiosis and fertrilization dictate the Mendelian Traits medelian patterns and inheritance An offspring receiving a dominant Proposed by theodere boveri and allele (whether it be homozygous or walter sulton heterozygous) will express the dominance Fundamental Principles Only those receiving homozygous Chromosomes sustain genetic alleles (both parents) will express the material recessive trait Chromosomes are replicated and Recessive traits may skip generations, passed from parent to offspring especially if its genotype is The nuclei of (most eukaryotic cells) heterozygous contain homologously: paired - Activated only when paired chromosomes with another who has the During gamete formation, different recessive allele types of nonhomologous chromosomes separate Each parent contributes one set of chromosomes to be offspring (half-dad and half-mom) Application to Mendel’s postulates Law of segregation - homologous pairs eventually separate during the process of meiosis