Biology 1101 (Intro to Biology) Midterm #1 Study Guide

Biology 1101 (Intro to Biology)Midterm #1 Study Guide

Introduction to Biology:Life follows an organized hierarchy, and this is the order, from the smallest unit, to the biggest composition:

atom molecule organelle cell** tissue organ organ system organism population community ecosystem biosphere

Living things acquire energy for 3 purposes:

build new structures repair old structures reproduce

All living things share these characteristics:

Organized in a specific way Need and acquire energy Maintain internal constancy Reproduce, grow, develop Living things (populations) evolve

Scientific Method:

Make observations Frame a question that relates

Propose a hypothesis Prediction (if… then…) Design and conduct an experiment Analyze your results and draw conclusions Submit for publication

When conducting an experiment to see if extra nutrients increases tree growth:

Sample size (how many trees? You want to have a good numberof trees so you can generate an average)

Variables Independent (manipulated) Variable: (nutrient in soil) Dependent (response) Variable: (amount of growth) Standardized Variables: (size of pot, amount of rainfall,

amount of sunlight.) Control treatment: The group that gets no fertilizer

Hypothesis: tentative, often narrow explanation regarding the natural world, which must be testable and falsifiable

Theory: a well substantiated explanation of some aspect of the natural world a unifying explanation for a spectrum of observations, hypothesis, or the ideas about which scientists aremost certain.

Chemistry of Life:Elements: pure substances that can’t be broken down by chemical means. (Examples include Hydrogen, Oxygen, Sodium, etc.)

Atom: the smallest component of an element. Composed of the following subatomic particles:

Neutron Proton (+) Electron (-)

Atomic number: the # of protons inthe nucleus.

When protons ≠ electrons, atom is an ion

Molecule: 2 or + chemically bonded atoms

ex: water

Electrons move around the nucleus in energy shells. 2 electrons fit in 1st energy shells, next 2 shells can hold 8 energy shells.

Octet Rule: atoms/ionsare most stable when they have 8 e- in outermost E shell (valence shell)

Basically, if this valence shell is filled with 8 electrons, it will be calm. If not, it will freak out and seek to gain an electron from another atom. This is how chemical reactions occur.

Nonpolar Covalent Bond: Both atoms have equal electronegativity (ability to attract electrons)

Ex: H2, CH4

Polar Covalent Bond: unequal sharing of electrons

Ionic Bond: Results from the electrical attraction between 2 oppositely charged ions.

Hydrogen Bond: A weak force of attraction between two atoms or ions with opposite partial charges.

Cohesion: When (water) molecules stick together, causing high surface tension.

Polar (hydrophilic) substances dissolve in water.

Non-polar (hydrophobic) substances do not.

Macromolecules: Organic molecules: are compounds containing both carbon and hydrogen. (Every single one contains these two elements.)

Polymers: chains (trains) created by linking subunits called monomers (train cars).

4 types of organic molecules:

OrganicMolecule

Purpose Monomers/Polymers

Composition

Carbohydrates Energy Simple Sugars(monomers)

Complex Carbs(polymers)

C6H12O6

Simple sugars arealso called

monosaccharides

LipidsLong-term energy

storage(fat/triglycerides),

growth anddevelopment

(sterols), cellmembrane coating(phospholipids).

Doesn’t really havepolymers or

monomers. (onlyorganic molecule tonot have anything)

consisting ofglucose, fructose,

and lactose.

Complex carbs arealso called

polysaccharidesconsisting of

starches, glycogen,and cellulose.

ProteinsVarious functions

Amino Acids(Monomers)Polypeptides(polymers)

20 different typesof amino acids thatcan form differenttypes of proteins.Each amino acidconsists of a

- central carbon atom- amino group- carboxyl group-hydrogen atomGroup called “R”

Nucleic Acids The purpose of DNA isto store genetic

information in orderto replicate oneselfand make proteins

Nucleotides(monomers)

2 types of nucleicacids in cells:

DNA, RNA

Phosphate group, 5-carbon sugar(deoxyribose),

nitrogenous base. 5of these

nitrogenous bases:Adenine, Guanine,Cytosine, Thymine(In DNA), Uracil

(in RNA)

Saturated fats contain all the H’s possible:

single bonds connect all the carbons solid at room temperature tend to be animal-derived

Unsaturated fats have ≥1 double bond b/t C’s

double bonds produce kink in chain liquid at room temperature tend to be plant-derived

Double-stranded helix (consider a ladder):

sugars and phosphates form the “rails” nitrogenous bases form the “rungs”

Cell Structure and Function:Cell Theory (Consists of 3 ideas):

1.) All organisms consist of one or more cells2.) he smallest unit of life that can function on its own3.) All cells arise from other cells

All cells share these characteristics:

1.) A cell membrane as a boundary2.) DNA as genetic material3.) RNA for protein synthesis4.) Ribosomes for protein manufacture5.) Proteins that do the cell’s work6.) Cytoplasm

So why is the cell membrane even important?

separates cytoplasm from exterior environment regulates what gets in and what goes out of cell and

maintains homeostasis within cell

THE 2 BIG CATEGORIES OF CELLS!

Prokaryotic Cells (Simple structure and small): No nucleus No membrane-bound organelles (no division of labor).

So, these organelles don’t have a separate job. They just all work cross-functionally in a blob of cytoplasm.

like an open warehouse distinct spaces for different tasks, but not separated

by barriers (membranes)

Eukaryotic Cells (Complex structure and larger): membrane-bound nucleus membrane-bound organelles Like an office separated into cubicles where each

“cubicle” performs its own function. cubicles = organelle

10-100 times bigger than prokaryotic cells each organelle is bound by a membrane that maintains

the internal environment1.) Nucleus : “executive boardroom”2.) Chloroplasts are organelles in plants and

algae that capture energy from the sun to produce food

3.) Mitochondria are the sites of cellular respiration

Prokaryote ≠ single cellular

Eukaryote ≠ multicellular

Endosymbiotic Theory:

Implications suggest that over time, genetic changes made the microorganisms incapable of living on their own, and that this interdependency lead to modern compartmentalized eukaryotic cells. How can we prove this is true though? Well there are 3 implications: Chloroplasts and mitochondria (which are consideredto be these ancestral prokaryotes):

1.) are similar in size to prokaryotes2.) have their own circular DNA3.) Reproduce by splitting in two

Metabolism: Energy: the ability to do work (move matter)

Potential energy: stored energy waiting to be used to do work or cause change.

chemical energy stored in food water behind a dam concentration gradient

Kinetic energy: energy of motion, used to do work

car in motion ions diffusing from low concentration water flowing any moving object

Chemical bonds hold potential energy

Metabolism: sum of all the reactions in cells

build new molecules, break down molecules

Photosynthesis & Cellular Respiration:

Living things constantly need energy:

producers consumers

Energy used is replaced by energy from the environment

Endergonic (“energy inward”) reactions:

Require energy to proceed Build complex molecules from simpler ones Reactants have less energy than products (Reactants [input]

< products [output]) Examples include photosynthesis

Exergonic (“energy outward”) reactions:

Release energy Break apart large, complex molecules Products have less energy than reactants (Products [output]

< reactants [input]) Aerobic respiration

What is ATP?

temporary chemical energy storage main energy carrier in cells “rechargeable battery” releases energy (exergonic)

Consists of:

adenine (N-base)

ribose sugar 3 phosphate groups

Photosynthesis: transforms light energy into chemical energy. Is used by plants, some protists, and some bacteria

Organisms that use photosynthesis are: Autotrophs “self-feeder.” The producers for most ecosystems

Light is the driving factor photosynthesis:

Why do leaves change colors?

As summer nears its end and daysget shorter, the increased amount of darkness incites trees

to prepare for a sort of hibernation. Leaves won't be able to continue photosynthesizing during winter due to the dry air and lack of sunlight, so the tree does two things. First, it forms a separation layer made ofcorklike cells at the base ofeach leaf to seal it off fromthe tree. Second, it stopsproducing chlorophyll since itwon't need this pigment untilthe days start to lengthen onceagain in the spring. Withchlorophyll out of the picture,the yellow and orange pigmentsget a chance to shine.

CO2 enters the leaf and O2 exits the leaf through holes in the leaf surface

Light dependent reaction:

Light is absorbed by photosystem, electrons excited

Electrons jump to electron acceptor molecule

Must replace electrons

– splits water

– releases oxygen

Electrons passed thruelectron transport chain

Energy is released each time electron ispassed