BIO-111 test 1

Steps of the Scientific Approach

Observation, Question, Hypothesis, Prediction, Experiment, Conclusion

Guess

An intuitive response with no scientific backing or testable form

Hypothesis

A proposed explanation for an observation that is testable and falsifiable. Must be based on prior knowledge

Prediction

"The specific, measurable outcome expected if the hypothesis is correct. Usually ""if…then…"" format"

Independent Variable

What the experimenter deliberately changes/manipulates. Plotted on the x-axis

Dependent Variable

What is measured/observed as a result. Plotted on the Y-axis

Controlled Experiment

Manipulates one variable; has an experimental group and a

control group. Best for establishing cause-and-effect

Comparative Experiment

Observes existing groups without manipulation (eg. comparing smokers vs. non-smokers). Cannot prove causation

Large sample size

Reduces sample error, more reliable results

Small sample error Data points cluster near the mean, more confidence in results

Cellular Organization

Made of one or more cells; cells are the basic unit of life

Metabolism

Carry out chemical reactions to obtain and use energy

Homeostasis

Growth and Development

Increase in size/complexity according to genetic instructions

Reproduction

Produce offspring, passing genetic information to the next generation

Heredity

Genetic information encoded in DNA is inherited

Respond to Environment

Detect and respond to stimuli

Evolution

Populations change over time via natural selection

Levels of organization (smallest to largest)

Atoms - Molecules - Cells - Tissue - Organs - Body Systems - Organism - Population - Community - Ecosystem - Biosphere

Four Most Common Elements in living Organisms

COHN - Carbon (18.5%), Oxygen (65%), Nitrogen (3.2%), Hydrogen (9.5%)

Carbon (C)

Backbone of all organic molecules; forms 4 covalent bonds - incredible diversity

Oxygen (O)

Highly electronegative; involved in respiration and polar bonds

Nitrogen (N)

Found in amino groups; essential for proteins and nucleic acids

Hydrogen (H)

Bonds with oxygen in water; 1 electron in outer shell

Proton

Neutron

Within the nucleus, 0 charge, contributes to atomic mass; differs in isotopes

Electron

In orbital (shells) -1 charge, Determines bonding behavior (valence electrons)

Atomic number

Number of protons

Atomic mass/weight

Protons + Neutrons

Isotopes

First shell holds…

Second shell holds…

Third shell holds…

Valence electrons

Electrons in the outermost shell - these determine bonding

Octet rule

"Atoms ""want"" 8 electrons in their outer shell - they bond to achieve this"

Carbon bonds

Nitrogen bonds

5 valence electrons, needs 3 more - forms 3 bonds

Oxygen bonds

Hydrogen bonds

1 valence electron, need 1 more - forms 1 bond&

Covalent bond

Ionic bonding

Hydrogen bonding

Nonpolar covalent

Slightly polar covalent

Definitely polar covalent

0.5-2.0

Likely ionic

Ion

An atom that has gained or lost an electron - now carries a charge

Cation

Positive

Anion

Cohesion

Water sticks to itself via H-bonds surface tension; allows water transport up plants

Adhesion

Water sticks to other surfaces - capillary action

High specific heat

Density change

Universal solvent

Hydrophilic

Hydrophobic

pH range 0-6

pH range 7

Neutral, H+=OH-, (eg. pure water, human blood (~7.4))

pH 8-14

Basic/alkaline (high pH), more OH- than H+, (eg. seawater (8), bleach (12))

pH

Measures the concentration of hydrogen ions (protons) in solution

Carboxyl

Amino

Hydroxyl

-OH, polar, hydrophilic (alcohol group); forms H-bonds (Found in: carbohydrates, proteins, and amino acids)

Methyl

Sulfhydryl

Phosphate

Carbohydrates

Mono saccharides (simple sugars), joined by glocosidic bonds, (energy storage (starch, glycogen); structural support (cellulose, chitin))

Lipids

Proteins

Amino acids, joined by peptide bonds, structural support; enzymes; transport; signals; movement

Nucleic Acids

Nucleotides, joined by covalent bonds, encode and store genetic information (DNA); gene expression (RNA)

Monosaccharides (simple sugars)

C6H12O6, polar, hydrophilic, dissolves in water, source of energy, (eg., glucose, galactose, fructose)

Glycoidic linkage

A covalent bond that joins sugar molecules together. Water (H2O) is released when the bond forms- this is condensation (dehydration) reaction. Two monosaccharides = disaccharide and many monosaccharides = polysaccharide

Starch

Glycogen

Glucose, animals (liver, muscle), energy storage in animals; rapidly mobilized to blood glucose

Cellulose

Glucose, plant cell walls, structural support; humans cannot digest it (diatary fiber)

Chitin

Triglycerides

Phospholipids

Steroids

4 fused carbon rings. Function as hormones (estrogen, testorsterone) and as cholesterol in membranes, Synthesized in the endoplasmic reticulum

Triglyceride structure

Glycerol - the 3 carbon backbone, fatty acid chains - long hydrocarbon chains (-CH2-) attached to glycerol, ester bonds - covalent bonds connecting each fatty acid to glycerol (R-O-CO-R)

Saturated fat 

Straight, packs tightly, solid at room temperature, makes membranes less fluid

Unsaturated fat

Kinked, can't pack tightly, liquid at room temperature, makes membranes more fluid

What type of bonds are found in a saturated fatty acid?

What shape is a saturated fatty acid chain and why?

Straight. Because there are no double bonds forcing the chain to bend anywhere, it hangs straight. Straight chains line up neatly next to each other and pack tightly together with no gaps between them

Why is a saturated fat solid at room temperature?

What type of bonds are found in an unsaturated fatty acid?

What shape is an unsaturated fatty acid chain, and what does that prevent?

Kinked/bent at the double bond - this prevents tight packing

What is the physical state of an unsaturated fat at room temperature?

Liquid, eg. vegetable oils, fish oils

How does an unsaturated fatty acid affect membrane fluidity?

It increases fluidity, making the membrane for fluid

What types of organisms tend to have more saturated fats, and why?

Warm-blooded animals - their body temperature is stable, so they don't need highly fluid membranes

What types of organisms tend to have more unsaturated fats, and why?

Cold-water fish - they need flexible membranes even in cold environments (eg., salmon vs. tilapia)

What bonds hold fatty acid side chains to glycerol in a triglyceride?

How do hydrocarbon chains in lipids associate with each other?

Van der Waals forces

Amphipathic

has both hydrophilic and hydrophobic regions

Core structure of membrane

Membranes: integral (intrinsic) proteins

Embedded in the bilayer; span it entirely (transmembrane)

Membranes: peripheral (extrinsic) proteins

Membranes: cholesterol

Membranes: carbohydrate chains