Biology Exam 1 PDF

**Biology Exam 1** **Taxonomy:** Science of classification of living things **Taxon (Taxa pl):** Classification level [Hierarchal System of Classification: ] Domain \-\-- Kingdoms\-\--Phylum\-\--Class\-\--Order\-\--Family\-\--**Genus\-\--Species** *Genus + species* = Scientific name called Bino...

**Biology Exam 1** **Taxonomy:** Science of classification of living things **Taxon (Taxa pl):** Classification level [Hierarchal System of Classification: ] Domain \-\-- Kingdoms\-\--Phylum\-\--Class\-\--Order\-\--Family\-\--**Genus\-\--Species** *Genus + species* = Scientific name called Binomial system **3 Domains** 2 prokaryotic (no nucleus) domains = Bacteria and Archea 1 eukaryotic (have nucleus) domain = Eukarya +-----------------------------------+-----------------------------------+ | Bacteria | Archea | +===================================+===================================+ | - Some good/ some bad | - Unicellular | | | | | - Everywhere | - Don't cause diseases | | | | | - Have Peptoglycan cell wall | - 3 types: 1) Extremophiles: | | | live in extreme conditions | | - Unicellular | (thermophiles, Halophile | | | (salty), pH tolerant or | | - Helpful for: digestion, | Pressure tolerant) 2) | | vitamin K, production of | Non-Extreme Archea: similar | | oxygen | as bacteria 3) Methanogens: | | | produce methane, poisoned by | | - Harmful: attach to cell, | oxygen | | syphilis | | | | - NO PEPTOGLYCAN CELL WALL | +-----------------------------------+-----------------------------------+ Domain of Eukarya = diverse What's sets them apart from prokaryotes? 1. Compartmentalization (more stuff inside such as nucleus or gene expressions) 2. Multicellularity (cell work together to do specialized things) 3. Sexual Reproduction (allows for genetic diversity) **6 Kingdoms** Bacteria and Archea (same as Domain) For domain of Eukarya the Kingdoms are: Plantae, Animalia, Fungi, Protista **Protista: Garbage** - Mostly Unicellular - Moist/ Aquatic environment - Colonial or multicellular **Plantae: plants** -Unique cell wall -Autotrophic, makes their own food by photosynthesis -Self-sufficient **Fungi: mold/mushrooms** -Heterotrophic, Absorbers -Decomposers = recycle -Parasites/ mutualists **Animalia: Animals** -Heterotrophic, ingestion **Biology =** Study of living things **[7 characteristics of the living ]** 1. Cellular Organization 2. Ordered Complexity 3. Sensitivity 4. Growth, reproduction and development 5. Homeostasis 6. Energy Utilization 7. Evolutionary Adaptation +-----------------------------------+-----------------------------------+ | **Cell Organization** | - All living beings are one or | | | more cells | | | | | | - Uses DNA as their genetic | | | information | | | | | | - Cells are the basic unit of | | | life | | | | | | - **[Ex: Mitosis and Meiosis | | | ]** | | | | | | - REMINDER: two type of cell | | | \-\-- Eukaryotic (has a | | | nucleus) and Prokaryotic (has | | | a nucleotide) | +===================================+===================================+ | **Ordered Complexity** | - Different kinds of cells with | | | different complex structure | | | (ex: tissue) | | | | | | - **[Cells work together to do | | | specific jobs ]** | | | | | | - Cell\-\--tissue\-\--organ\-\- | | | -organ | | | system\-\--organism | +-----------------------------------+-----------------------------------+ | **Sensitivity** | - Sensitive to stimuli = | | | ability to respond to change | | | in the external environment | | | | | | - Ex: pupil dilatation | +-----------------------------------+-----------------------------------+ | **Growth, Repro + Development** | - Capacity to grow and | | | reproduce (mitosis and | | | meiosis) | | | | | | - Hereditary molecules (DNA) | | | are passed on, genes (unit of | | | inheritance that is | | | transmitted to the offspring) | | | | | | - Reproduction = new cells or | | | new individual | +-----------------------------------+-----------------------------------+ | **Homeostasis** | - Maintain constant internal | | | condition that are different | | | from the environment | | | | | | - Ex: body shivers when cold | +-----------------------------------+-----------------------------------+ | **Energy Utilization** | - Take in of energy to do work | | | | | | - Types: Heterotroph (take food | | | from others by ingestion or | | | absorption) & Autotroph (make | | | their own food) | +-----------------------------------+-----------------------------------+ | **Evolutionary Adaptation** | - Descendants from common | | | ancestors (view Darwin's | | | Theory) | | | | | | - Evidence from fossil | | | | | | - The difference in | | | characteristics is due to | | | Natural Selection | +-----------------------------------+-----------------------------------+ **[Viruses:]** are not alive +-----------------------------------+-----------------------------------+ | **Cell Organization** | - No cells | +===================================+===================================+ | **Ordered Complexity** | - Yes, are made of molecules | +-----------------------------------+-----------------------------------+ | **Sensitivity** | - No | +-----------------------------------+-----------------------------------+ | **Growth, Repro + Development** | - Yes/no they need an | | | intermediate | +-----------------------------------+-----------------------------------+ | **Homeostasis** | - No | +-----------------------------------+-----------------------------------+ | **Energy Utilization** | - No | +-----------------------------------+-----------------------------------+ | **Evolutionary Adaptation** | - Yes/No need a host | +-----------------------------------+-----------------------------------+ **Hierarchal Organization** [Cell level]: atoms (basic unit of matter) \-\-- molecules (made of atoms) \-\-- macromolecules (complex biologic molecules such as DNA, proteins, fats) \-\-- organelles (structure of the cell) \-\--Cell (basic unit of life) [Organism level:] tissue (group of cells that work together for a particular function) \-\--organ (different tissues that work together) \-\--organ system (organ that work together) \-\--organism (vary in size and complexity can be a single cell or billions of cells) [Population level:] Population (group of species that live in the same place) --\-- Species (all population of a particular organism that can interbreed and a similar appearance) \-\--Community (different species living at the same place) \-\--Ecosystem (community of organism in a specific area and **their interaction with the surroundings**) \-\-- Biosphere (all the ecosystem on the planet) **Steps of the Scientific Method:** 1. Observation 2. Ask questions 3. Develop Hypothesis 4. Test Hypothesis 5. Make predictions 6. Conclusion 7. Peer Review **Hypothesis:** tentative to answer a well framed question and can be proven wrong \*Can never be true because new evidence can lead to disprove How to test the hypothesis? -Must have variable (dependant, independent, controlled) -two subjects (test and control) \- minimum of 3 replications of the test **The 3 P's** **Problem Posing:** *asking a question that can be tested* **Problem Solving*:*** *designing an inquiry process to test the hypothesis* **Peer Persuasion:** *Convincing other of the validity of your conclusion* **[A Theory is:]** supported by a large body of evidence, broader than a hypothesis and general (can lead to another testable hypothesis) Example of important discoveries with the scientific method +-----------------------------------+-----------------------------------+ | Louis Pasteur | - Invented pasteurization | | | | | | - Germ hypothesis: organism in | | | the air can contaminate broth | | | and cause things to grow | | | | | | - Control: the seal on the | | | flask is broken therefore | | | nothing abnormal about the | | | broth = can go bad | | | | | | - Replication: Done in many | | | flasks, this ensure that the | | | results are true and not just | | | a coincidence | | | | | | - Controlled Variables: all | | | flasks are treated the same | | | way except for the broken | | | flask left intact | | | | | | - Independent Variable: Access | | | of bacteria into the broth | | | | | | - Dependant Variable: Broth | | | goes bad or not | | | | | | - Repeatability: Protocol is | | | written down so other can do | | | it | +===================================+===================================+ | Charles Darwin | - Theory of Evolution through | | | Natural Selection | | | | | | - Observations: characteristics | | | of different species varied | | | from place to place, meaning | | | exterior factors played a | | | role in diversity. Ex: 14 | | | different species of finches | | | = all different beaks | | | | | | - Assumption: Different species | | | had common ancestors and the | | | change in their | | | characteristics is due to | | | descent by modification | | | | | | - Hypothesis: Evolution occurs | | | due to the mechanism of | | | Natural Selection | | | | | | - Observations that lead to | | | hypothesis: All species would | | | overpopulate, therefore there | | | was a limited supply of | | | resources. The individual | | | with better adapted | | | characteristics, would | | | survive (Natural Selection). | | | These "better" | | | characteristics are passed | | | from generation to | | | generations. | | | | | | - Evidence from Darwin: | | | | | | 1. Common Ancestor: variations | | | in related species living at | | | different location | | | | | | 2. Artificial Selection: | | | producing individual with | | | desirable characteristics | | | (breeding stock) | | | | | | 3. Geology: the earth was very | | | old, therefore subtle changes | | | could happen over long | | | periods of time. | | | | | | 4. Fossil: evidence that change | | | happened | | | | | | 5. Pop growth vs Resource | | | Availability: Only a limited | | | number of offspring could | | | survive and produce further | | | offspring depending on their | | | characteristics =natural | | | selection | | | | | | - Jointly presented their ideas | | | in London and Darwin | | | published work | | | | | | - Supporting Modern Evidence: | | | | | | 1. Fossil Record: new fossil are | | | found everywhere | | | | | | 2. The age of the Earth: Now we | | | know the earth id about 4.5 | | | billion years old | | | | | | 3. Mechanism of Heredity: | | | Mendel's theory of genetic | | | inheritance | | | | | | 4. Comparative Anatomy: Related | | | organisms have the same | | | structure from the common | | | ancestor: **Homologous | | | Structures** = same | | | evolutionary origin, | | | different structure and | | | function. (same thing but | | | different needs) **Analogous | | | Structures:** similar | | | structure and structure but | | | different origin (same need | | | different structure) | | | | | | 5. Molecular Evidence: all life | | | has DNA as hereditary | | | material. Related individuals | | | = similar DNA and proteins. | | | Evolutionary history of an | | | organism is based on genes = | | | phylogenetic tree | | | (resemblance in genes) | +-----------------------------------+-----------------------------------+ **Cell Theory** 1. All living things are composed of one or more cells, and the life processes of metabolism and heredity occurs within these cells. 2. Cells are the basic unit of life 3. Cell arises only by division of preexisting cells Cell are very small: REMINDER 1um = 10-6m -Bacteria from 1 to 5 um -Animal cell about 50 um -plant cell about 100 um WHY SO SMALL? Cells work at all time (have reaction going inside them at all times). They need oxygen and materials to make product and must remove the waste product **Cell surface:** is where the materials go in and out Since the volume of the cell increases faster than its area, it takes material longer to be diffused. The ratio of surface area needs to meet the metabolic need. Hence why cells are so small. **Resolution:** ability to differentiate two objects when you view them **Microscopes:** optical instrument that uses a lens or combination of lenses to magnify and resolve details of an object (first created by Anthony von Leeuwenhock) [Types of microscopes ] +-----------------------+-----------------------+-----------------------+ | **Light Microscope | Use light that passes | The light of the | | (LM)** | through the specimen | microscope goes | | | and glass to magnify. | through the DIAPHRAGM | | | | which acts as a lamp | | | Can be used for live | shape (cuts scattered | | | specimens | light) Then, the | | | | light goes through | | | | the | | | | [condenser]{.underlin | | | | e} | | | | which is a lens that | | | | focuses the light | | | | onto the specimen | +=======================+=======================+=======================+ | **Electron Microscope | A beam of electrons | - **Transmission | | (EM)** | passes through the | Electron | | | specimen | Microscope:** | | | | | | | Revealed organelles | | | | and sub features of | | | | the cell | - **Scanning | | | | Electron | | | | Microscope:** | +-----------------------+-----------------------+-----------------------+ **3 characteristics of all cells** *[Plasma membrane, cytoplasm and DNA]* +-----------------------------------+-----------------------------------+ | Prokaryotic Cell | Eukaryotic cell | +===================================+===================================+ | - Bacteria and Archea cells | \- complex cells, larger | | | | | - Simple unicellular small | \- have organelles | | | | | - Has cytoplasm, DNA and Plasma | \- Types such as plant or animal | | membrane | | | | \- Nucleus with double membrane | | - Rigid cell wall\*\* | (nuclear envelope) | | | | | - Flagella | \- Ribosomes | | | | | - Nucleoid | \- some have flagella and cell | | | walls | | - Ribosomes | | +-----------------------------------+-----------------------------------+ \*\* Bacteria has a peptoglycan cell wall that can be destroyed with penicillin (NOT ARCHEA) Flagella: permits motion looks like a long string [Plasma Membrane ] Flexible outer boarder of the cell Made of phospholipids, proteins and cholesterol held by weak bonds Has **Selective Permeability** which permits material from going in and out [Cytoplasm ] Semifluid matrix made of organelles (have secific function) and cytosol (75% water and 25% proteins) Site of many chemical reaction Give shape of the cell [Organelles ] Specialized structures inside the cell (factory) [Nucleus (Boss Office)] Largest organelle found in all eukaryotic cells Is the control center, contains DNA (chromosomes or chromatin) Nucleolus: makes ribosomes Nucleoplasm: liquid where DNA is found Nuclear envelope: membrane of nucleus with pores [Nuclear Envelope ] Separates nucleus from the rest of the cell (like plasma membrane but for nucleus) Nuclear pores : allows for the passage of RNA and ribosomes [DNA] Hereditary material, specifies cell structure and function Chromatin = extended form of DNA Chromosome = condensed form of DNA [Nucleolus ] Directs the synthesis of RNA and forms ribosomes [Endoplasmic Reticulum (ER)] Assembly line Has two part : +-----------------------------------+-----------------------------------+ | Rough Endoplasmic Reticulum | Smooth Endoplasmic Reticulum | +===================================+===================================+ | - Bumpy with ribosomes | - No bumps | | | | | - Is all around the nucleus | - Tied to the rough ER | | | | | - Contains ribosome | - Builds sugar and fats | | | | | - Produces proteins an | - Steroids hormones | | membranes | | | | - Assembles membrane lipids | | | | | | - Detoxification of drugs | +-----------------------------------+-----------------------------------+ THE PRODUCT OF THE ER ARE MADE FOR EXPORT [Vesicule:] taxi for molecule in the cell [Ribosomes] Made in nucleolus Site of protein synthesis in Rough ER Has a large subunit and a small subunit made of rRNA and protein [Golgi apparatus ] Collects, packages, and distributes molecules (finition) Newly formed products end up in cisternae (membrane fold of the Golgi) +-----------------------------------+-----------------------------------+ | Lysosome | Peroxisome | +===================================+===================================+ | - Produced by Golgi | - Hydrogen peroxide!! | | | | | - Enzymes and low pH | - Breakdowns amino acids and | | | fatty acids | | - Breakdown old organelles, | | | digest particles, recycles | - Smaller than lysosome | | material within the cell | | | | | | - Garbage men | | +-----------------------------------+-----------------------------------+ [Mitochondria] About the size of a bacteria found in both plant and animal cells Reproduces on its own has its own DNA Power of the cell by converting glucose into energy (ATP which is cellular respiration) [Chloroplast ] Cite of photosynthesis (mostly in plants) Give green pigment Takes CO2 H2O and sunlight and turns it into CO2 H20 and 02 HAS ITS OWN DNA Stroma = inner material of chloroplast Have closed compartments of stacked membrane called grana with disk = where photosynthesis happens [Centrosomes ] Area of cellular division near the nucleus where microtubules [Centrioles] Help assemble microtubules Build up into mitotic spindles during mitosis and meiosis NOT IN PLANT AND FUNGI [Cytoskeleton ] Protein fibers that anchor the organelles and support the cells Have 3 types : Actin, microtubules, intermediate filaments *Actin* Are in muscle, responsible for contraction *Microtubules* Cell movement, move material within the cell Structure of cilia and flagella *Intermediate filaments* Provide structural stability, protection and durability Difficult to break [Cilia and Flagella ] Cilia = multiple short hair Flagella = long string Used for movement ONLY FLAGELLA IN HUMAN = sperm Cilia = respiratory system, uterine tubes [Vacuoles ] In plants: used for storage of water, sugar ions etc In protists: contractile vacuole = regulates water content in the cell [Cell wall ] Hard and rigid around the plasma membrane Bacteria = peptoglycan Plant and Protist = Cellulose Fungi = Chitin **Origin of life** -Life first appeared between 3.8 and 2.5 BYA (fossils) \- Earth had a reducing atmosphere = lots of reactions = easy to form bonds \- lots of lightning and intense UV radiations Called [primitive soup ] 4 main stages of the formation of cells: 1. The abiotic (non-living) formation of organic molecules such as amino acid and nucleotides 2. These small molecules joined = macromolecules such as proteins and nucleic acids 3. Protobionts (fat droplet) surrounded these molecules and maintained the internal chemistry 4. Origin of self-replicating molecules eventual made inheritance possible (RNA) Miller and Urey experiment can serve as evidence for this theory - They simulated earth atmosphere at that time = formation of simple compounds such as amino acids - Found over 30 molecules Earliest cells where prokaryotes similar to archea and their DNA was very different **Bacteria** Arrived about 2 BYA - Strong walls of peptoglycan - Some where photosynthetic = cyanobacteria - Increased oxygen in atmosphere **Earliest Eukaryotic cells** Evolve from prokaryotic cells = formation of nucleus and organelles (more complex) HOW? Origin of Nucleus = infolding of the plasma membrane in the prokaryotic cell Origin of Mitochondria and Chloroplast = Energy producing bacteria come to live inside the prokaryotic cell = evolves into mitochondria (same for chloroplast) **Endosymbiosis Theory = Theory of formation of eukaryotic cell** Evidence = mitochondria and chloroplast have their own DNA Very similar to prokaryotic cell = ribosome inside mitochondria, similar genome, similar in size Replicate by binary fission (same as bacteria) Review Chemistry: Everything is made of matter = chemicals which form structural component **Elements of living things: CHNOPS** **C**arbon, **H**ydrogen, **N**itrogen, **O**xygen, **P**hosphorus, **S**ulfur Molecules = 1 or more atoms, compounds = different atoms together 3 types of bonds: Covalent, ionic and hydrogen +-----------------------+-----------------------+-----------------------+ | Covalent | Ionic | Hydrogen | +=======================+=======================+=======================+ | - Sharing of | - Positive and | - Weak bond | | electrons | negative ions | | | | | - Helps hold | | - Can be 2 of the | - One electron | molecules | | same or 2 | giver and one | together | | different | electron receiver | | | | | - Usually between a | | - Polar or | | hydrogen and an | | non-polar | | highly | | depending on | | electronegative | | electronegativity | | atom (O, N, F) | | (one electron | | | | pulls the | | | | electron cloud | | | | towards them) | | | +-----------------------+-----------------------+-----------------------+ Structure of water 2H and 1 O = polar molecule Why is water important in biology? 1. Allows other molecules to move around 2. Life lived in water 3. 2/3 of organism's body is made up of water 4. Organism can reproduce and grow in water **Properties of Water** +-----------------------------------+-----------------------------------+ | Cohesive behavior | - Due to hydrogen bonds water = | | | sticky | | | | | | - Allows for the transport of | | | water against gravity (in | | | plants goes up the root) | | | | | | - Adhesion = attraction between | | | different surfaces | | | | | | - Surface tension = cohesion of | | | water at its surface (small | | | insect can walk on water) | +===================================+===================================+ | High specific heat | - Water has a high specific | | | heat = needs lots of energy | | | to go up 1C | | | | | | - Helps modulate temperature of | | | organism | | | | | | - When water absorb heats the | | | hydrogen bonds break = leads | | | to high specific heat | +-----------------------------------+-----------------------------------+ | High heat of vaporization | - Many hydrogens bond must be | | | broken before vaporization = | | | evaporation causes cool | | | surface = effective coolant | | | for animals (sweating) | +-----------------------------------+-----------------------------------+ | Lower density of ice | - Ice floats because is less | | | dense = allows for living | | | being to live in oceans = | | | possibility of life on earth | +-----------------------------------+-----------------------------------+ | Solubility | - Water is polar = versatile | | | solvent | | | | | | - Can dissolve big compounds | | | such as proteins | | | | | | - Hydrophilic = love water vs | | | Hydrophobic = hate water | +-----------------------------------+-----------------------------------+ [Water + buffers ] Most organism have a pH of 7 while organic fluids have a pH range of 6 to 8 In humans the buffer is carbonic acid and water = maintain the balance of 7 **Organic compounds** Compounds made of carbon backbone Usually with hydrogen and oxygen, can also have phosphorus, sulfur and nitrogen What's cool with carbon = 4 bonds leads to long chains of carbon **Properties** 2 influences = length + shape of backbone and functional group Functional group = group of atoms with particular properties Ex : -OH (Hydroxyl), -C=O (carbonyl), -COOH ( Carboxyl), NHH (Amino), Mehytl CH3, Phosphate P-R, Sulfhydrhyl = S-H Hydroxyl and Carboxyl - Polar and hydrophilic Carboxyl = weak acid and water soluble Amino group - Basic Phosphate group = weak acid Macromolecule = chains of monomer -- polymers **Monomers** Single unit = monomer Chain of component = polymers +-----------------------------------+-----------------------------------+ | **Dehydration Reaction** | **Hydrolysis Reaction** | +===================================+===================================+ | - Formation of polymers | - Covalent bonds are broken | | | | | - Covalent bonds | - Energy released = water added | | | to the polymer | | - Energy required to remove | | | water | - Creates monomer for digestion | | | | | - Condensation | | +-----------------------------------+-----------------------------------+ **Types of macromolecules** 1. Carbohydrates 2. Proteins 3. Lipids 4. Nucleic Acid - Sugar = C1 H2 O1 - Energy storage - Different complexity = monosaccharides, disaccharides, polysaccharides [Monosaccharides ] - Monomers of sugar - Triose (3 carbons), Pentose (5 carbons), Hexose (6 carbons) - 3 types : glucose (animal) , galactose (used as is in mitochondria) , fructose (plants) [Disaccharides ] - 2 monosaccharides together - Storage - Ex : glucose + fructose = sucrose , glucose + glucose = maltose (bread), glucose + galactose = lactose [Polysaccharides ] - Storage of carbohydrates - Ex : Starch made by plants , cellulose (cell wall of plants), chitin (cell wall for fungi and arthropods), glycogen (animals storage) **Lipids** - Fats - All hydrophobic - Protect, insulate and provide energy 3 types of lipids: - Natural fats - Phospholipids - Steroids - Terpenes (plant oils) [Natural fats ] - Can be saturated or unsaturated - Fats and oils (common name) *Saturated fat = solid at room temp= in animal* - 1 glycerol and 3 fatty acids chain - ALL CARBONS HAVE H BONDS (molecule is complete) *Unsaturated fat = oil at room temp = in plants* - As C=C therefore not all H bonds (molecule is incomplete) - Liquid at room temperature **Note :** we have enzymes to break down both fatty acids (good) but Trans fatty acids cannot be broken down by our organism = bad [Phospholipids ] Main component of biological membrane 2 fatty acid and 1 glycerol + phosphate group Hydrophilic because of phosphate group [Steroids ] 4 carbon rings fused together Ex: cholesterol in cellular membrane = assimilated in liver source of steroid hormones **Nucleic Acids** Made of nucleotides = monomer Either DNA or RNA Made of ; Pentose, nitrogenous base and phosphate group +-----------------------------------+-----------------------------------+ | Deoxyribonucleic acid | Ribonucleic acid | +===================================+===================================+ | - Double stranded | - Single stranded | | | | | - Sugar= deoxyribose | - Sugar = ribose | | | | | - Base = A,G,C,T (Adenine, | - Base = A, G, C and U | | Guanine, Cytosine, Thymine) | (Adenine, Guanine, Cytosine | | | and Uracil) | | - Carries genetic info | | | | - Transmission of DNA info | | - Double helix because A always | | | binds to T and G binds to C | | | the different combination of | | | A-T and G-C leads to | | | different information | | +-----------------------------------+-----------------------------------+ **Proteins** - Amino acids = monomer - Polymer of amino acid are linked with peptide bonds (covalent) - 20 different types - Made of: an amino group, a carboxyl and a side chain - The side chain determines the amino's properties [Functions of proteins ] 1. Catalysis = enzymes catalyse rxn 2. Defense = antibodies 3. Transport = hemoglobin (transport oxygen in blood) 4. Support = intermediate filaments = keratin 5. Motion = muscles movement 6. Regulation = hormones, turn gene on and off 7. Storage = calcium and iron are stored in proteins **Central Dogma of Biology = flow of information in a cell** From DNA --\-- to RNA \-\-- to Protein **Cell division** [Mitosis ] - All cells must reproduce - Result in 2 identical daughter cells - Different in prokaryotes and eukaryotes **Bacterial Cell division** - Called binary fission - Create a single chromosome in the nucleoid - Replicates the chromosome - The chromosome separates on each side of the bacteria - Creation of a **septum (new cell wall) = division of the bacteria** **Genome =** all the DNA in a cell (total amount+ function) **Chromosome =** condensed form of chromatin, forms before cellular division **Chromatin =** 40% DNA 60% protein = contains DNA information **Karyotype =** number of chromosomes possessed by an individual Human = 2 different set off chromosomes =23 mom + 23 dad EACH CELLS OF HUMAN HAS 46 chromosomes **Haploid =** complete set of single chromosome = n **Diploid =** complete set of mom and dad = 2n **Homologous chromosome =** maternal and paternal set of chromosomes **Copies of chromosome = chromatids** Before DNA replication, *[1 chromosome = 1 chromatid (single finger)]* After replication, *[1 chromosome = 2 sister chromatids (double finger in x)]* The sister chromatids are tied by a centromere in the middle The **Kinetochore** = where the microtubules attached during anaphase on the outer portion of the chromatid In binary fission = replication and division occur as one process In eukaryotes = DNA replication occurs early, and separation happens later because replication of organelles In unicellular cell = division of 1 cell = 2 new organisms In eukaryotes depends on why: 1. Growth 2. Fertilized egg 3. Tissue renewal/ repair **Cell cycle** **Interphase = G1, S and G2** - Gap 1 = cell growing = extensive synthesis of organelles - S phase = replication of DNA = sister chromatids - Gap phase 2 = continuous cell growth M phase = mitotic phase (when cell divides) = 4 phases - Prophase - Metaphase - Anaphase - Telophase Go = exit from cell cycle (non-dividing cell) +-----------------------------------+-----------------------------------+ | Prophase | - DNA condenses into | | | chromosomes | | | | | | - TWO SISTER CHROMATIDS | | | | | | - Nuclear envelope breaks down | | | | | | - Spindle apparatus start to | | | assemble | | | | | | - Centriole move to each pole | | | of the cell | | | | | | - No nucleolus golgi and ER are | | | dispersed | +===================================+===================================+ | Metaphase | - Chromosomes align at the | | | midpoint of the cell called | | | metaphase plate | | | | | | - The spindles attached to the | | | kinetochore | +-----------------------------------+-----------------------------------+ | Anaphase | - Centromeres break and | | | chromatids are separated | | | | | | - They chromatids are pulled | | | apart at opposite ends from | | | the cell | +-----------------------------------+-----------------------------------+ | Telophase | - Spindle starts to disappear | | | | | | - Nuclear envelope starts to | | | form back | | | | | | - Chromosomes begin to uncoil | | | | | | - Cytokinesis \* | +-----------------------------------+-----------------------------------+ \*Cytokinesis is not a phase but is the final action: \- Is the cleavage when the cell divides in two halves \- Animal = cleavage furrow \- plant = formation of cell plate (new cell wall) PLANTS AND FUNGI DON'T HAVE CENTRIOLES BUT SPINDLE FIBERS DO STILL FORM **Meiosis** **Somatic (body cell) =** 2n do mitosis **Gametes =** reproductive cells do meiosis [Gametes are haploid = 1n] **Sexual reproduction =** fusion of two gametes which results in a new organism MEIOSIS PERMITS GENETIC VARIABILITY Meiosis goes through the same phase as mitosis but twice without a second interphase **Interkinesis = pause after first division** **IN MIOSIS 1, there is genetic recombination (crossing over)** +-----------------------------------+-----------------------------------+ | Prophase 1 | - Homologous pairs (chromosomes | | | made of sister chromatids) | | | pair up in a hup (synapsis) | | | and form tetrads | | | | | | - **Crossing over** = between | | | mom and dad chromosomes | | | (non-sister chromatids) | | | | | | - **Chiasmata** = site of | | | crossing over | +===================================+===================================+ | Metaphase 1 | - The spindle attaches to the | | | kinetochore of each homologue | | | (chromosomes) | | | | | | - Separations of the tetrads | | | | | | - The separation of chromosomes | | | is random | +-----------------------------------+-----------------------------------+ | Anaphase 1 | - Sister chromatids remain | | | attached to each other | | | | | | - the chromosomes are double | | | stranded | +-----------------------------------+-----------------------------------+ | Telophase 1 | - **same as mitosis** | +-----------------------------------+-----------------------------------+ | Prophase 2 | - **same as mitosis** | +-----------------------------------+-----------------------------------+ | Metaphase 2 | - **same as mitosis** | +-----------------------------------+-----------------------------------+ | Anaphase 2 | - **same as mitosis** | +-----------------------------------+-----------------------------------+ | Telophase 2 | - **same as mitosis** | +-----------------------------------+-----------------------------------+ During interkinesis, there is no replication of DNA Cytokinesis in Meiosis = each daughter cell has now 1 set of chromosomes = haploid (1n) 4 main features of meiosis: 1. Synapsis and crossing over 2. Sister chromatids remain joined at their centromeres 3. Kinetochores of sister chromatids are attached to the same pole 4. DNA replication does not happen during interkinesis Mitosis Meiosis ------------------------------------ ----------------------------- 2 daughter cells with 2n 4 daughter cells with 1n Somatic cells Gametes No exchange of DNA during prophase Crossing over in Prophase 1 1 cell division 2 cell division **Meiotic errors** [Nondisjunction] = when a pair of homologous fails to separate = abnormal number of chromosomes in a cell = usually leads to death [Aneuploidies:] Diploid cell plus or minus a given n can lead to trisomy 21 Number of chromosome and chromatids during cell division PARENT CELL = 46 chromosomes w/ 1 chromatid Meiosis Mitosis Prophase 1 = 46 chromosomes w/2 chromatids Prophase = 46 chromo w/2 chromatid -------------------------------------------- --------------------------------------- Metaphase 1 = 46 chromo w/ 2 chromatids Metaphase = 46 chromo w/ 2 chromatid Anaphase 1 = 46 chromo w/2 chromatids Anaphase = 46 chromos w/ 2 chromatids Telophase 1 = 23 chromo w/ 2 chromatid Telophase = 46 chromos w/ 1 chromatid Prophase 2 = 23 chromo w/ 2 chromatid Metaphase 2 = 23 chromo w/ 2 chromatid Anaphase 2 = 23 chromo w/2 chromatid Telophase 2 = 23 chromo w/ 1 chromatid