Key: Purple for extra information, this information is not on the summary slides. Do not confuse that purple with this pink which I use in other pages for differentiation. Note: There are a few pictures from the slides that I didnt include her3 because I don’t understand them at all so skip those at your risk. Chapter 9: Chromosome Duplication: Interphase Cycle [Eukaryotic] = • Cell prepares for cell division. • • Most of the cell cycle is spent in interphase. Nerve & Muscle cells don’t complete the cell cycle, they remain in G0 Stage. S stage: - DNA synthesis: Two identical DNA molecules - Chromosomes are internally duplicated. 👇 - Chromosomes start the phase with one chromatid each then they end up as sister chromatids. - At the end of this stage, sister chromatids align at the centromere. M Stage (Mitosis & Cytokinesis) = - Mitosis : - Centromeres and sister chromatids seperate, - Daughter chromosomes are distributed to two daughter nuclei. - The daughter nuclei get the same number of chromosomes as the mother cell. [Images are too self-explanatory to be summarized Apoptosis (Cell death, decreases cell numbers, opposite of cell division) = - De nition: Sequence of events in the cell that cause its destruction - Occurs if DNA is damaged and cannot be repaired in G2 Stage - Caused by enzymes called caspases Steps: 1. Cells that are dying round up together 2. Their nucleus collapses and fragments [nucleus falls apart] 3. Chromatins condense 4. Plasma membrane blisters (swells and forms blebs (small balls of uid)) 5. The cell fragments and these fragmented cells contain fragments of DNA Cytokinesis Division of the cytoplasm. Animal Cytokinesis = - Divides mother cell’s cytoplasm into two equal daughter cells - Daughter cells are encased in plasma membrane - Anaphase might follow 1. Cleavage furrow between daughter nuclei 2. Formed by a ring of actin laments 3. Pinches the mother cell in two Plant Cytokinesis = 1. Cell plate forms 2. Furrowing impossible due to rigid cell walls outside the plasma membrane. 3. Golgi apparatus produces small membrane-bounded vesicles. 4. These vesicles fuse and become one thin vesicle surrounding the mother cell. 5. Cell plate and plasma membrane fuse. Now daughter cells have plasma membrane. 6. Middle lamella lls space between daughter cells. 7. Daughter cells secrete original cell walls on the opposite sides of the middle lamella. Prokaryotic Cell Division = - The chromosome of a prokaryote is ring of DNA and associated proteins. - The chromosomes are folded up in the nucleoid. fl fi fi fi fi Binary ssion: the splitting in two of a prokaryote. 2 replicate chromosomes ͢ 2 daughter cells (identical). Chapter 10: Meiosis = The number of chromosomes would double each new generation if there was no reduction of chromosomes in meiosis. Phases of Meiosis 1 [When homologous chromosomes pair up in synapsis]= + synapsis: fusion of chromosomes, they recombine or exchange genetic material. + One diploid parent cell ͢ Two haploid daughter cells Crossing-over: exchange of genetic material between non-sister Prophase 1: chromatids in Meiosis 1. - Spindle forms - Nucleus disappears - Chromosomes duplicate - Homologous chromosomes synapse [fuse] Metaphase 1: - Homologous pairs arrange at the metaphase plate [Equator] - Then they align independently of one another Anaphase 1: - Homologous pairs separate - Sister chromatids don’t separate though - Chromosomes are reduced from diploid to haploid Telophase 1: - Daughter cells have one duplicated chromosome from each homologous pair Phases of Meiosis 2 = + DNA is not replicated between Meiosis 1 & 2 + Two haploid parent cells ͢ Four haploid daughter cells Prophase 2: - Chromosomes condense Metaphase 2: - Chromosomes align at metaphase plate Anaphase 2: - Centromere dissolves - Sister chromatids separate and become daughter chromosomes (not duplicated). Telophase 2 + Cytokinesis: - Results in four haploid daughter cells - Gametes contain a mixture of maternal and paternal genes In relation to animals = + Meiosis occurs only during gametogenesis [cells undergo meiosis to form gametes] + Spermatogenesis: production of sperm + Oogenesis: production of eggs ff + Asexually reproducing organisms need mutations in order to have o spring with genetic variation. + Genetic variation is essential for a species to evolve and adapt. + Meiosis uses crossing-over and independent assortment in order to create genetic variation. + Trisomy: when an individual has three of a particular type of chromosome. Ex. Down syndrome (aka. trisomy 21) + Changes in sex chromosme number is a result of nondisjunction during oogenesis or spermatogenesis. + Turner syndrome: female with 1 X chromosome. Missing X chromosome. + Klinefelter syndrome: XXY. Male with underdeveloped testes. Extra X chromosme. Chapter 11: • Gregor Mendel performed cross-pollination experiments using homozygous plants • Monohybrid cross: cross dealing with one contrasting (di erent) trait • Law of segregation: a parent produces one allele for a gene in each gamete they produce. [because pairs of alleles separate from each other during meiosis] P = Parental Generation F1 = First lial generation o spring F2 = Second lial generation o spring ff ff ff fi fi Punnett square: a table that lists all possible genotypes that can result from a cross. - sperm genotypes on one side and egg genotypes on the other. zygotes inside the squares. - Recessive phenotype - Dominant phenotype ͢ Homozygous recessive genotype ͢ (Either homozygous dominant or heterozygous) genotype Testcross: determines the genotype of individuals with a dominant phenotype - Autosome: any chromosome that’s not a sex chromosome - Autosomal dominant disorders : if you have recessive genes on autosomes then you don’t have it [From 1 parent] - Autosomal recessive disorders : if you have dominant genes on autosomes then you don’t have it [From 2 parents] Chapter 12: - DNA helicase enzyme: separates the two strands of DNA - DNA primase enzyme: places short primers on the strands that will be replicated - DNA polymerase enzyme: recognizes RNA & begins DNA synthesis - Single-stranded binding proteins (SSB): attach to newly separated DNA strands and prevent the formation of the double helix + The two strands are replicated di erently; one being leading strand other being lagging strand. + Leading strand is the new one, and is synthesized 2x faster than the lagging strand + Daughter DNA molecule always contains one old strand and one new strand. + Okazaki fragments: short sections of DNA formed during synthesis of the lagging strand. + mRNA (messenger RNA): sends message from DNA in nucleus to ribosomes in cytoplasm. + tRNA (transfer RNA): transfers amino acid to ribosomes. + rRNA (ribosomal RNA): ribosomal proteins + rRNA = ribosomes ⃪ synthesizes polypeptides. - Genetic code: consistes of codons. - Codons: unique arrangements of three RNA nucleotides, which contain 1 of the 4 nitrogenous bases. - A codon codes for 1 of the 20 amino acids. - UAA, UGA, UAG codons are stop codons. AUG codon is the start codon. DNA ͢ RNA Transcription ͢ Protein Translation Occurs in nucleus Occurs in cytoplasm ff gene expression Transcription = - occurs in the nucleus Three stages: + Initiation • RNA polymerase binds to a promoter (region of DNA that starts transcription, its direction, and strand) + Elongation • RNA polymerase attaches complementary RNA bases as it moves down the template strand. + Termination • RNA polymerase reaches a DNA stop sequence and releases the mRNA molecule [messenger RNA] Translation = - occurs in the cytoplasm, more speci cally in a ribosome. - Ribosome has 3 binding sites for tRNA and 1 binding site for mRNA. Facilitate complementary base pairing between tRNA anticodons + mRNA codons Initiation Stage - mRNA codon sequence ͢ protein (amino acids) sequence + mRNA codon sequence tells us the order of amino acid chain and which amino acids are necessary. - mRNA transcript is read by the ribosome. - tRNA molecules carry amino acids to mRAN in order to form protein. fi - Ribosome reaches a stop codon. Termination Stage Elongation Stage Chapter 13: Prokaryotic Regulation: - Bacteria do not always require the same enymes. - Enzymes are produced as needed. - Operon model explains gene expression regulation in prokaryotes. (Developed by Francois Jacob and Monod, 1961) - An operon is a group of structural and regulatory genes Componenets of an Operon (RPOS) Regulatory Gene - Just one gene Promoter Operator - Short segment of - Codes for a repressor DNA sequence protein which where RNA activates or polymerase rst deactives the operon attaches - Located outside the operon - Short segment of DNA sequence where active repressor protein binds Structural Genes - Long segment of DNA which code for enzymes of a metabolic pathway. - One or many genes transcribed simultaneously trp Operon Two cases: fi Tryptophan amino acid absnet - Repressor protein unable to attach to operator (repressor inactive) - RNA polymerase binds to promoter - Enzymes for tryptophan synthesis are produced Tryptophan amino acid presnet - tryptophan binds with repressor protein - They are now called corepressors - Repressor active and blocks synthesis of enzymes for tryptophan synthesis - RNA polymerase cannot bind to promoter Eukaryotic Regulation: - Uses many mechanisms. 5 primary levels of control = 1. 2. 3. 4. 5. Chromatin structure Transciption control Posttranscriptional control Translational control Posttranslational control Nuclear Levels [ Transcription ] Cytoplasmic Levels [ Translation ] Chromatin Structure: - Eukaryotic DNA 🤝 histone proteins - Nucleosome: DNA wrapped around a group of 8 histone proteins. - Look like beads on a string. Beads are the nucleosomes. - Nucleosome coiling determines level of chromatin packing. Makes up chromatin. Euchromatin - Loosely coiled DNA - Transcription active Heterochromatin - Tightly packed DNA - Transcription inactive - Barr body: inactive X chromosome in females. Tightly packed length-wise. - Females have XX. One is a Barr body and the other one is active. X-Inactivation in Mammalian Females: - Females have two x chromosomes - Cell division seperates active X chromosomes from In active X chromosomes (Barr bodis). DNA Unpacking Process: She might ask to label this. Gene Mutation: - Permanent change in the sequence of nitrogenous bases in DNA. (A,G,C,T) - Either doesnt a ect protein activity or completely shuts it down. Germ line mutations → sex cells Somatic mutations → body cells Spontaneous Mutations Induced Mutations - Chemical changes in DNA - Replication errors - Transposons move from one - Caused by mutagens location to another - Rare occurence (1 in a billion) because of DNA polymerase correcting erros. Point Mutations - Substitution of a nitrogenous (radiation, organic chemicals, base in one DNA nucleotide etc) - Muragens can be carcinogens OR - Environmental Mutagens = - Change of one codon to food, tobacco smoke, etc. another. ff ff Proteins would ither become inactive, less active, or not a ected. Chapter 14: - Biotechnology: Use of natural biological systems to create a useful product. Allows scientists to modify, edit, or clone genomes of organisms. Either improves the characteristics of the organism or creates a product. - Genetically modi ed organism (GMO): organism whose genome has been modi ed [Self-Explanatory] [Usually by recombinant DNA tech] - Transgenic organism: GMO that had a gene from another species inserted into its genome. Recombinant DNA technology Recombinant DNA (rDNA): DNA from two di erent sources. + This technology requires a vector, restriction enzyme, and DNA ligase enzyme. Vector: introduce rDNA to host cell. Example: Plasmids. - Plasmids: small accessory rings of DNA from bacteria Restriction enzyme: Cleaves (cuts) DNA. Creates opening. The DNA fragments end in segments with sticky ends which allow for the insertion of foreign DNA into vector DNA. DNA ligase enzyme: seals DNA into openeing. (Foreign DNA 🤝 Vector DNA) - Result is recombinant DNA - Host cell takes up recombined DNA. - Gene cloning occures. Many copies of vector and foreign gene. - Cloning: production of identical copies of DNA/cells/organisms. Example: Identical twins [single embryo ͢ two embryos]. Bacterial colony on a petri dish. [one cell - Gene cloning: production of identical copies of 1 gene. ͢ bacteria colony] + We can recover a cloned gene or protein product if the inserted gene is replicated or expressed. - Polymerase Chain Reaction (PCR): copies/duplicates/clones targeted sequences fi ff fi of DNA. Requires DNA polymerase (to seperate strands) and supply of nucleotides (for new complementary strand). - Gene therapy: procedures that give patients good genes to replace bad genes. uses genes to treat genetic disorders and other illnesses. ex vivo gene therapy method: outside the body. in vivo gene therapy method: inside the body. Uses of ex vivo gene therapy Examples/uses of in vivio gene therapy - treating infected bone marrow stem cells -treating cystic brosis - treating children with SCID - nasal spray (treatment) - treating familial hypercholesterolemia - liposomes (treatment) - lentiviral vectors (treatment) fi * words are multicolored for reading purposes using syllables.
