Bio 101 Midterm

  1. Into to Scientific Method

Scientific Method Steps

  • Make an observation

  • ask a question

  • form a hypothesis that answers the question

  • make a prediction based on the hypothesis

  • Do an experiment to test the prediction

  • Analyze results

Benefits of Scientific Knowing’s

  • Testable (test hypothesis)

  • Reproduceable ( what’s true for me should be true for another researcher)

  • Isolatable (test a single variable at a time)

  • Unbiased ( without outside influence)

Drawbacks of Scientific Knowing’s

  • Some things are Unique ( only occurring once)

  • Some experiences are subjective ( Art)

  • Some things are found without seeking ( love)

  • Some things may only be accessible within yourself ( strengths, weaknesses)

Observation: Something you observe with your senses ( sight, hearing, smell, touch , taste)

Hypothesis: A suggested explanation for an event

Prediction: What you think the results of an experiment will be. Also has the format “ If (black) then (blank) .

  1. Scientific Method 

Intro to Scientific Experiments 

  • Variable: Things that can vary ( distance, weight, sex, size, color temp, etc.) 

  • Categorical Variable: Things that fall into distinct groups (gender, species, food.)

  • Quantitative Variable: Numerical/ can fall on a number line( age, height, weight, number of offspring) 

  • Categorical/ Quantitative Experiment = Bar graph 

  • Quantitative/Quantitative Experiment = scatterplot 

  • Independent Variable: what you control in the experiment 

    • on x ais 

  • Dependent variable: Results from changes in the independent variable

  • How to remember Independent/Dependent 

    • “I want to look at the effects of ____on____.

  • Control Group: shows what would happen in an experiment  under normal conditions  without any interventions. 

    • controls all variable except the independent variable 

    • provides a bassline comparison 

    • allows for the result to have no interference 

  • Experimental Group:  shows what would happen in an experiment under abnormal conditions with interventions. 

  • Negative Control: Produces no expected result/ response which could mean contamination 

  • Positive Control: Produces an expected result which confirms the experiment is functioning properly 

  1. The Study of Life

Traits Associated with Life

  •  Growth

  • Reproduction

  • Excretion

  • Evolution

  • Homeostasis

  • Metabolism

  • DNA

  • Made of Cells

  • Movement

  • Heredity

  • Responds to stimuli

The textbook definition makes it difficult to identify Aliens as “alive” because its based on earths chemistry and processes( cells and DNA) which an alien might not share.

Scientist believe all life is related because all cellular organisms have many genes in common.

“All Life is apart of a tree” expresses that we all had the same starting point, and after time branched out into our own respective categories.

All life on earth is considered equal with no Hierarchy.

  1. Macromolecules and enzymes 

Different Hypothesis for the Origin Of Life

  • Primordial Soup Hypothesis:  Oxygen levels were once low and complex molecules could not be broken down. When these complex molecules like Ammonia, hydrogen and methane were stimulated with lightning/solar energy, amino acids/DNA components were created. This was experimented by Muller Urey. 

  • Deep Sea Vent Hypothesis:  Life began in deep sea volcanic vents spewing hot sulfur and other chemicals.  Volcanic materials + Water ≈ Organic Material 

  • Frozen Life Hypothesis: Life began in ice because ice can protect organic molecules from radiation and other harmful elements. when in ice, Cyanide + Small chemicals =Adenine (nitrogenous base)

  • Clay Hypothesis: Scientist believing life originated from crystals. Crystals = Atoms arranged in highly specific patterns and when replicated the patterns continue. ( like human life) 

  • Deep Hot Biosphere Hypothesis:  Life started miles below earths surface. Lithotrophs and roundworms are able to live miles within the earth, and earth is very rich containing many minerals. 

  • Alien Hypothesis: Meteors, space dust, and comets have been known to contain RNA and DNA and amino acid components.

Protein 

  • Many amino acids make up the complex molecule called a protein 

    • Amino Acid: monomer 

    • Protein: polymer 

  • 20 Amino acids can create the 100,000 Proteins in the body because there are many different combination variations. 

  • Structural protein: Provides Rigidity, Strength, and architectural support. 

    • Ex. Keratin( Nails, hair), Collogen( Bones, Ear structure), Silk Fibers( webs, shirts)

  • Contractile Proteins: ( Motor Proteins) Act as little motors, burns chemical energy to create movement 

    • Ex: muscle contraction 

  • Enzymes: Proteins that power up reactions, or in other words Catalyst 

Carbohydrates (sugars)

  • Many Monosaccharides make up a complex Molecule called a Polysaccharide 

    • Monosaccharide: Monomer 

    • Polysaccharide: polymer 

  • Carbohydrates( sugars) act as most organisms primary source of energy 

  • Storage carbohydrates:  an organism stores extra sugar in its body for later use in the form of a large carbohydrate polymer.

    • glycogen: storage carb for animals

    • Starch: storage carb for plants 

  • Architectural Carbohydrates: Organisms can use large carbohydrate molecules for armor/support

    • cellulose( sheet of glucose molecules) plant cell walls( only cows and termites can digest)

    • chitin fungi cell wall (made with sting of glucose derived molecules)

  • Lipids( fats)

  • Triglycerides are made of glycerol molecule connected to 3 fatty acids.

    • Triglyceride: polymer

    • Fatty acids: monomer 

  • Triglycerides: Function is long term energy storage

  • Steroids: sex hormone

    • cholesterol: maintains fluidity in cell membrane 

  • Phospholipids: forms cell membrane which controls what enters and leaves the cell

  • Saturated fats: Single carbon bond

    • Solid at room temp ( butter, coconut oil, lard) 

    • common energy storage in animals

  • Monounsaturated fats: Have one double bond 

    • liquid at room temp because they don’t pack together nicely (oil)

    • Common energy storage in plants  

  • Polyunsaturated fats: Have multiple double bonds 

    • liquid at room temp

What is Food and why do we Eat it?

  • We eat because food is a source of energy( sugars fats, and proteins)

    • sugars, fats, and proteins are broken down to give us ATP

    • ATP: powers everything in our cells

  • Heterotrophs: Eats other living things for energy 

    • Humans, parasites, and decomposers 

  • Autotrophs: Makes their own food (plants, bacteria)

    • Photoautotrophs: Uses sunlight energy to make food(photosynthesis)

    • Lithotrophs: organisms that consume nonliving material (bacteria) 

  • High Carbohydrate foods: Fruits, potatoes, plants

  • High Protein foods: chicken, peanuts 

  • High Fat foods: Plant oils, butter 

  • Chemical indicator: A chemical that changes color in response to a chemical/chemical reaction

Endothermic: absorbs energy 

Exothermic: Releases energy 

Panspermia: The idea that life travels through space from planet to planet 

Monomer: Singular molecule 

Polymer: many Molecules 

Organic Molecule: Carbon rich molecule that makes up the body of living things 

Catalyst: speeding up rates of reactions without them being lost 

substrate: Molecule that attaches to an Enzyme ( like lock and key)

  1. Cells and Organelles 

  • Single Celled Organism: made up of one cell ( bacteria, algae, protozoa) 

  • Colonial: Made of multiple cells  similar in function 

  • Multicellular: made of many cells that are different from each other ( plants, animal)

  • Prokaryotic cells

    • small

    • No cell membrane 

    • Cell wall 

    • no bound nucleus or organelles 

  • Eukaryotic Cells

    • can be small or large 

    • has cell membrane

    • ( only plant based eukaryotic cells have cell walls)

    • membrane bound nucleus and organelles 

Organelle: Cells Organs 

  • Cell Membrane: (factory walls)

  • Phospholipid Bilayer

    • selectively permeable( only allows certain molecules to pass through

  • Nucleus: (Blueprints Safe)

    • Houses DNA

      • nucleolus is involved in making ribosomes

  • Mitochondria: (power generator)

    • powerhouse of the cell

      • converts sugars into ATP

      • sight of cellular respiration

      • They are symbiotic bacteria with their own bacterial genome 

  • Endoplasmic Reticulum: (assembling Area)

    • Rough ER: Has ribosomes covering it, RNA copies goes here to instruct what protein to make

    • Smooth: Make lipids and carbohydrates

  • Golgi Apparatus: (Packaging Center)

    • Packages proteins in Vesicles (lipid packages)

      • vesicles can leave the cell

    • attaches “address labels” to molecules to indicate where they go next

  • Cytoskeleton: (Support structure)

    • provides support for the cell

    • acts as the vesicles conveyer belt to move through the cells

  • Chloroplast : organelles in plants and algal cells that conduct photosynthesis

  • Endosymbiotic Theory: Chloroplast and mitochondria are symbiotic bacteria inside cells

    • explains origin of eukaryotic cells

  1. Diffusion and Osmosis 

  • Active transport: Requires ATP 

  • Passive transport: Doesn’t require ATP, moves willingly 

  • Diffusion: Occurs so that molecules move from an area of high concentration to an area of low concentration to create Equilibrium

    • Diffusion is important for breathing( respiration) because it allows for the exchange of O2( Oxygen) and CO2 ( carbon dioxide)

    • small organisms / thin skinned organisms obtain oxygen across their body surface, therefore not requiring respiratory systems 

    • Hotter the temp faster the diffusion rate  - Lower the temperature, slower the diffusion rate 

  • Osmosis: water moving from high to low concentration across the membrane 

    • Hypertonic solutions: water moves from high to low causing cell to shrink

    • Isotonic Solutions: water moves in both directions equally so cell doesn’t change size

    • Hypotonic Solution: Water moves from low concentration to high concentration causing cell to swell up

6.Photosynthesis  

  • Light:  a form of radiant energy ( it radiates out) made of electromagnetic waves 

  • Chemical energy: Energy contained within chemical bonds 

  • Pigments: chemicals that absorb some wavelengths of light and reflect others 

    • plants use photosynthetic pigments to capture light energy

    • Opsins: pigments responsible for perceiving light (found in retina)

    • Melanin: skin pigment that protects against UV damage, and reason for different hair, skin, and eye colors 

  • Photosynthesis 

    • Takes place in the mesophyll layer

    • Chloroplast: converts light, CO2 and water into sugars for plants

    • Thylakoids: green pancake stacks inside chloroplast ( embedded with chlorophyll pigment) 

  • Photosystem 2

    • When light hits chlorophyll it excites its electron 

    • The energy from the electron passes from one chlorophyll molecule to another (electron transportation chain)

    • The electron transportation chain converts light energy into chemical energy

    • As electrons pass through the thylakoid they collect protons, as the protons hit a proton bump they escape and create ATP with the energy release 

  • Photosystem 1

    •    The electron is passed from photosystem 2 to Photosystem 1

    • 2 excited electrons join together (H+) to (NADP+) to create NADPH

    • NADPH is then used in the Calvin Cycle  for its 2 energy electrons and its hydrogen atom to create G3P

    • G3P is produced by the Calvin Cycle which and  ATP and NADPH are used up

    • G3p Is used to create a molecule to feed back into the Calvin Cycle and they can join with each other to create glucose, starch or cellulose ( carbohydrates

7.Cellular Respiration 

  • Cellular Respiration

    • Reactants: Glucose and oxygen

    • Products:  Carbon Dioxide, Water, and ATP

    • Occurs in the cytoplasm and mitochondria of the eukaryotic cell

    • Purpose: to make ATP 

  • ATP: Adenosine Triphosphate

    • Fuels everything in the body as far as energy

  • Glycolysis: 

    • Initial chemical: glucose

    • Final product: Pyruvate 

  • In the course of Krebs Cycle, ATP, NADH, and FADH2 are produced 

    • NADH and FADH2 power the electron transport chain by giving up their electrons

    • The electrons then pass through the mitochondria, collecting protons into the intermembrane simultaneously 

    • when to many protons accumulate they “escape” to the mitochondria and that movement creates ATP

  • Cellular Respiration: Endothermy 

    • instead of protons returning to the proton pump( like in the Krebs Cycle) they take an alternative route making all the energy release as heat instead of turning into ATP

  • Anaerobic respiration 

    • Used when a cell does not have access to oxygen

    • Fungi/ Animal Anaerobic Respiration is Lactate Fermentation 

    • Lactate fermentation turns glycolysis into a looping process when oxygen is not available.

      • Ex: if your muscles ran out of oxygen because of a heavy workout, lactate fermentation would

  • Other molecules( fats/ amino acids) can be broken down into energy by feeding into cellular reparation

  1. Mitosis 

  • Mitosis: The separation of duplicated chromosomes into two nuclei 

    • Creates 2 identical diploid daughter cells 

    • Diploid: 2 sets of chromosomes 

  • Cytokinesis: Division of one cell into two 

    • Happens alongside telophase

      • Plant cells: happens by the pinching of the middle of the cell

      • Animal Cells: happens by building a cell plate in the middle 

  • DNA: blueprint for the body 

  • Genes: a tiny piece of DNA that codes for a protein 

  • Chromosome:  Long organized structures of DNA

    • Humans have 46 chromosomes ( 23 pairs)

    • 22 from each parent(44) and 2 sex chromosomes ( 46 total)

  • Alleles: different versions of genes 

  • Homologous Chromosomes: similar  pair of chromosomes in diploid organisms 

  • Sister Chromatids: the  identical duplicated chromosomes made during S phase

  • I (Interphase):  cell forms and a nucleus is present. Prepares for division

  • P (Prophase):  Chromosomes condense and become visible, the nuclear envelope breaks down, and spindle fibers form  

  • M (Metaphase): The chromosomes align in the middle of the cell with each attached to a spindle fiber 

  • A (Anaphase): The spindle fibers shorten, pulling the sister chromatids apart to the opposite poles of the cell

  • T (Telophase) : New Nuclear envelopes form around the separated chromosomes, and they begin to decondense

9:Meiosis 

  • Meiosis: 

    • Produces 4 Haploid Cells ( gametes)

    • Haploid: one set of chromosomes 

    • Only occurs once 

    • Produces cells that differ from parent cells

    • have half the number of chromosomes as parent cells 

  • Prophase 1:

    • Synapsis: Homologous chromosomes pair up and cross over to exchange genetic material

      • This result in chromosomes being completely different than how they started

  • Metaphase 1:Chromosomes line up in the middle of the cell with the homologous pairs still attached 

  • Anaphase 1: The homologous pair separate 

    •     homologous pairs have independent assortment

    • independent assortment: separates independently of each other

  • Telophase 1: Two new nuclei form ( with two chromosomes in each hence 2nd cell division)

  • Meiosis has two cell division events.

    • Anaphase 2: Sister chromatids separate 

10.DNA

  • Nucleic Acid: polymer

    • Nucleotide: monomer 

  • DNA:

    • Nitrogenous Bases: Adenine (T), Guanine(C), Cytosine(G), Thymine(A) 

    • Double helix

    • Replication: DNA create replica of itself 

    • Transcription: The information contained in one of the DNA strands is transferred into messenger RNA

    • Translation: The information contained in the messenger RNA is read and used to create a protein 

  • RNA: 

    • Nitrogenous Bases: Adenine(T), Guanine(C), Cytosine(G), Uracil(A) 

    • Single strand 

  • Alleles:

    • Human carry 2 alleles for each gene because they get one from each parent 

    • 22 (Mom), 22(Dad), 2 sex chromosomes 

11.Genetics 

  • Alleles: 

    • Dominant Allele: Presence of one allele masks the effects of the other 

    • Recessive Allele: presence of one allele is masked by the other 

    • Heterozygous: One dominant and one Recessive allele

    • Homozygous Dominant: 2 dominant alleles

    • Homozygous Recessive: 2 recessive alleles 

    • Codominance: Both alleles are expressed 

    • Incomplete Dominance: Heterozygotes have a trait halfway between two alleles

  • Genotype: The genes you carry in your body 

  • Phenotypes: All Observable characteristic of a person

  • Mendelian Inheritance: genes are NOT affected by events of your life

  • Lamarckian Inheritance: Disproven idea that you pass on acquired characteristics 

  • Genes: what are passed down from parent to offspring

  • Phenotype Plasticity: Ability to have multiple phenotypes with the same genotype 

    • Sex Linked Traits: Characteristics determined by genes located on the X or Y chromosome.