Intro to Biology (college) Exam 1

What are the characteristics common to all living things?

• All living things are made of cells

• All living things are organized and made of the

same molecules

• All living things grow, develop, and reproduce

• All living things use raw materials, produce, and use

energy

• All living things respond to the environment

• All living things maintain homeostasis

• Populations of living things evolve

what determines if something is a science?

• Focuses on the natural world

• Aims to explain the natural world

• Uses testable ideas

• Relies on evidence

• Usually leads to ongoing research

• Involves the scientific community

What does science do?

it aims to understand the natural

world through observation and reasoning

What are two major types of reasoning used in science?

• deductive reasoning- from general to

specific

• inductive reasoning- from specific to

general

What are the main steps of the scientific method?

- Observation

- Hypothesis

- Prediction

- Experimentation

- Conclusion

hypothesis

possible explanation for an

observation

prediction

what you expect if your hypothesis were true

peer review

people who read an article and provide feedback

basic research

is intended to extend the boundaries of what we know

applied research

- Foundation provided by basic research

- May involve the manufacture of food

additives or drugs

Hypothesis vs. Theory

• Hypotheses - proposed explanations for a narrow set of phenomena

• Theories - broad explanations for a wide range of

phenomena. Theories integrate and generate many

hypotheses.

What are some types of evidence that support the Theory of Evolution through Natural Selection?

How did the atmosphere of early earth differ from now?

Popular view of early atmosphere:

• Carbon dioxide

• Nitrogen gas

• Water vapor

• Hydrogen gas

• Other sulfur, nitrogen, and carbon compound

Current atmosphere:

• Nitrogen

•Oxygen

• Argon

• Carbon dioxide

• Other trace molecules.

What did Miller-Urey experiment demonstrate?

reproduce early atmosphere

Where are some current hypotheses for the source of the first biological molecules?

what are microspheres and why are they important in understanding the origin of life?

they are pre-cells.

What was the first probable genetic material?

RNA

What are the first fossil signs of life on earth?

• 3.7 BYA by stromatolites (BY= billion years)

• 3.0-3.1 BY fossil cells

• 1.3-1.8 BY First complex cells (with organelles)

• 700 MY Multicellularity

What are stromatolites?

structures produced by

microorganisms by trapping of sediments and other particles

What is matter?

Anything that has mass and occupies space

What are elements?

basic building blocks of matter that cannot be broken down by chemical means.

What is an atom and what is its structure?

the smallest unit of an element that

still has all the properties of that element. consists of 3 types of subatomical particles (protons, neutrons, electrons)

What is the atomic number

# of protons

atomic mass

# of protons and neutrons

What are isotopes and how do they differ from each other?

Atoms of same element with different

number of neutrons.

What is the octect rule?

• The inner shell holds only 2 e-

• The outer shell of each atom can hold 8 e-

• Atoms are more stable if they fill their outer shell

• Unpaired e- make an element reactive

What makes an atom stable or reactive?

Atoms are more stable if they fill their outer shell

Unpaired e- make an element reactive

What are ions, cations and anions?

ion- Atoms may lose or gain electrons

Cations - are positively charged ions

Anions - are negatively charged ions

What is oxidation, reduction, and how to these names relate to electron giving and receiving?

oxidation- losing electrons (give)

reduction- gaining electrons (receive)

What are molecules and what are compounds?

• Molecule: two or more atoms

that share e-

• Compound: molecule of 2 or

more elements

How do ionic bonds differ from covalent bonds?

Ionic bonds

• Charged atoms = ions

• Opposite charges

attract

Covalent bonds

• Strongest bond type

• Atoms share valence electrons and satisfy the octet

• Strength of bond depends on # shared electrons

Which electrons are shared in covalent bonds?

valence electrons

What are the different types of covalent bonds?

polar and nonpolar

What is the difference between polar and nonpolar molecules?

• Nonpolar: electrons are equally shared (atoms

have similar electronegativity)

• Polar: shared electrons spend more time around

one of the nuclei (atoms have different

electronegativity)

What are chemical reactions and what influences their rate (speed)?

Making or breaking chemical bonds and Transferring atoms from one molecule to another without change in the atom

Influenced by:

1. temperature

2.Concentration of reactants/products

3. catalysts (enzyme)

What are hydrogen bonds?

hydrogen of a water molecule

and oxygen of another water

molecule

What are some important properties of water and how do they relate to life?

1. Water has a high specific heat

2. Water has a high heat of vaporization

3. Solid water is less dense than liquid water

4. Water is a good solvent

5. Water can form ions

6. Water molecules are cohesive and adhesive

What is cohesion

water

molecules stick to

other water molecules

by hydrogen bonding

what is adhesion?

water

molecules stick to

other water molecules

by hydrogen bonding

What is pH? How does pH value vary in acids and bases?

convenient expression of [H+] of a solution

(acidic)0-14(basic)

What is an acid

Any substance that dissociates in water to increase

the [H"]

what is a base?

Substance that combines with H" dissolved in water,

and thus lowers the [H"]

What is a buffer and why does it matter for maintaining homeostasis?

Substance that resists changes in pH

What are polymers?

• Long molecules

What are monomers?

Made from chemical

bonds between smaller

subunits

What are the 4 major types of biological macromolecules?

carbohydrate

nucleic acid

protein

lipid

What are the major functions of carbohydrates?

-Quick energy source for the cell

• Short-term energy storage

• Important in maintaining health of digestive system

What are the atoms found in carbohydrates?

Carbon, Hydrogen, Oxygen

monosaccharides

Monomer

disaccharides

2 monomers joined by a covalent bond

polysaccharides

several monomers joined by covalent

bonds

What is one characteristic common to all lipids

Lipids do not mix with water

What are the atoms found in lipids?

Made of C, H and O with a large number of C-H

bonds.

What are the main functions of lipids?

-Energy storage

• Found in the membrane of cells

• Steroids are lipids

How do fats differ from oils?

• Fats : solid at room temperature; with saturated fatty

acids.

• Oils: fluid at room temperature; with unsaturated fatty

acids.

saturated fatty acids

unsaturated fatty acids?

What are phospholipids and what do we mean when we say they are amphipatic?

glycerol+ 2 fatty acids+ phosphate group.

• Main component of biological membranes

amphipathic= Hydrophobic + hydrophilic

regions

Where do we usually find phospholipids?

What are some examples of steroid molecules?

• Cholesterol

• Testosterone

• Estrogen

What are proteins and what are the subunits of proteins?

Macromolecules with amino acid subunits

connected by peptide bonds.

What are different functions of proteins?

support,

enzymes, transport, defense, movement

What are the different levels of protein organization?

1. Primary structure - sequence of amino acids

2. Secondary structure - interaction of groups

in the peptide backbone

3. Tertiary structure- further folding of the

polypeptide

4.Quaternary structure- two or more

polypeptides joined

What are chaperone proteins?

help other proteins to

fold

what is denaturation and how can you denature a protein?

proteins unfold and lose

structure and function.

Caused by:

• High temperatures

• High/Low pH

• High salt concentrations

What levels of protein structure are lost during denaturation?

What are nucleic acids and what are their subunits?

- macromolecules specialized in the

storage, transmission and use of genetic information.

polymers of nucleotides.

What different types of nucleic acids do you know?

What are the nitrogenous bases found in DNA and RNA?

DNA- deoxyribonucleic acid

• RNA- ribonucleic acid

DNA

Contains the genetic code

• Double helix - 2 polynucleotide strands connected by

hydrogen bonds

- Base-pairing rules

• A with T

• C with G

RNA

RNA similar to DNA except

- Contains ribose instead of deoxyribose

- Contains uracil instead of thymine

• Single polynucleotide strand

• RNA specifies sequence of amino acids in proteins

What are the chemical reactions that make polymers or that break polymers down?

• Dehydration synthesis

- Monomers are joined to form polymers

- Forma3on of large molecules by the removal of water

• Hydrolysis

- Polymers are broken down to monomers

- Breakdown of large molecules by the addi3on of water

What are the principles of cell theory?

1. All organisms are composed of cells

2. Cells are the smallest living things

3. Cells arise only from pre-exis3ng cells

What the main features of prokaryotic cells?

• Lack a membrane-bound nucleus

- DNA is present in the nucleoid

• Cell wall outside of plasma

membrane

• Do contain ribosomes (not

membrane-bound organelles)

• Two domains of prokaryotes

- Archaea

- Bacteria

How do bacteria differ from archaea?

• Most bacterial cells are encased

by a strong cell wall

-composed of pep3doglycan

• Archaea lack pep3doglycan

• Archaea membranes are

different from bacterial ones

prokaryotic cells

eukaryotic cells

• Possess a membrane-bound nucleus

• More complex than prokaryo3c cells

• Hallmark is compartmentaliza3on

- Achieved through use of membrane-bound

organelles and endomembrane system

• Possess a cytoskeleton for support and to maintain

cellular structure

What is the function of the nucleus of the cell?

Contains gene3c informa3on (DNA

and RNA)

What are ribosomes and what do they do?

Cell's protein synthesis machinery

• Found in all cell types

• Ribosomes may be free in cytoplasm or associated

with internal membranes

• A ribosome is made of Ribosomal RNA (rRNA) and

proteins

What are the components of the endomembrane system and what are their functions?

Rough endoplasmic reticulum

(RER)-Synthesis of proteins to be

secreted, sent to lysosomes

or plasma membrane

• Smooth endoplasmic reticulum

(SER)

• Relatively few bound

ribosomes

• Variety of func3ons-

synthesis, store Ca2+

,

detoxification

Golgi apparatus

• Functions in

packaging and

distribution of

molecules

• Vesicles transport

molecules to

destination

Lysosomes

• Membrane-bounded digestive

vesicles

• Arise from Golgi apparatus

• Enzymes catalyze breakdown

of macromolecules, cells or

foreign maKe

What are vacuoles and in which cells do you find them?

• Membrane-bounded

structures in plants Various functions

depending on the cell

type (prokaryotic?)

What are mitochondria and their major function?

• Found in all types of eukaryo3c cells

• Bound by membranes

- Outer membrane

- Intermembrane space

- Inner membrane has cristae

- Matrix

• On the surface of the inner membrane, and also

embedded within it, are proteins that carry out

oxida3ve metabolism

• Have their own DNA

What are the functions of chloroplast

• In cells of plants and

some other eukaryotes

• Contain chlorophyll for

photosynthesis

• Surrounded by 2

membranes

• Thylakoids are sacs

within the inner

membrane

• Have their own DNA

What are the major components of the cytoskeleton and their function?

• Network of protein fibers

found in all eukaryotic cells

- Supports the shape of the cell

- Keeps organelles in fixed

locations

• Three types of fibers:

• Microfilaments (Actin

filaments)

• Microtubules

• Intermediate filaments

In what cell types do you find a wall?

How are cells connected to each other?

What is the basic structure of the plasma membrane?

Phospholipids arranged in a bilayer

• Proteins inserted in the lipid bilayer

• Fluid mosaic model - mosaic of proteins floats in or

on the fluid lipid bilayer

• The membrane

allows some

things in while

keeping other

substances out.

What kinds of proteins do you find in the plasma membrane?