BIO Exam 1

Variable

Any part of the experiment that can vary or change during the experiment

Independent variable

Component that is predicted to cause or be responsible for the observed phenomenon; can be manipulated or changed by the researcher

Dependent variable

Component that is predicted to change in response to the independent variable; this variable is what we measure and record as data

Bar chart

Compares data between categorical variables

Standard error bars

Show the uncertainty (precision) of the estimated mean

Treatment group

The group that receives the manipulation

Molecule

ANy substance consisting of two or more identical or different atoms

Covalent bonds

Atoms share one or more valence electrons

Methane

1 carbon is covalently bonded to four hydrogens; each hydrogen atom now contains two shared electrons in valence shell, carbon atom contains 8 shared electrons in valence shell

Electronegativity

An atom’s attraction for the electrons in a covalent bond

Nonpolar covalent bond

Atoms share the electron equally

Polar covalent bond

One atom more strongly pulls electrons toward itself; the atoms do not share the electron equally, causes a partial positive or negative charge for each atom or molecule

Electronegativity of common elements

O > N > C

pH

Tells us how acidic or basic a solution is; it’s based on the amount of hydrogen ions (H⁺)

Lower pH

Acidic, higher hydrogen ion concentration

Higher pH

Basic, lower hydrogen ion concentration

Carbon

Subtle differences in structure can have large effects on biological function

Isomers

Compounds with the same molecular formula but different structures

Structural isomers

Different covalent arrangements of their atoms

Geometric isomers (cis-trans isomers)

Have the same covalent bonds but differ in their spatial arrangements

Enantiomers

Isomers that are mirror images of each other

Stability and flexibility

Why is carbon essential to life?

Energy storage

Hydrocarbons store large amounts of chemical energy in their covalent bonds

Functional diversity

Carbon bonds easily with H, O, N, P, and S, enabling the formation of biologically essential functional groups

Functional groups

a specific cluster of atoms within a molecule that dictates the molecule's characteristic chemical reactions and physical propertie

Structural complexity → biological complexity

Carbon’s bonding patterns allow life to build enzymes, membranes, genetic material, and signaling molecules

Carbohydrate

Monosaccharides

Glucose, fructose; Functions: Fuel, carbon sources that can be converted to other molecules or combined into polymers

Dissacharides

Lactose, sucrose; Functions: fuel, carbon sources that can be converted to other molecules or combined into polymers

Polysaccharides

Cellulose strengthens plant cell walls, starch stores glucose for energy in plants, glycogen stores glucose for energy in animals, chitin strengthens animal exoskeletons and fungal cell walls

Nucleic acids

Store and transmit information

Components of nucleic acids

Monomer (nucleotides), sugar, nitrogenous bases, structure

Components of DNA

Phosphate group

Pentose sugar

Deoxyribose

Nitrogenous bases [Cytosine (C), Guanine (G), Adenine (A), Thymine (T)]

Sugar-phosphate backbone; polarity (usually double-stranded)

Function: Stores hereditary (genetic) information

Components of RNA

Phosphate group

Pentose sugar

Nitrogenous base

Ribose

Nitrogenous bases [Cytosine (C), Guanine (G), Adenine (A), Uracil (U)]

Sugar-phosphate backbone; polarity (usually single-stranded)

Function: Performs various roles in gene expression

Primary protein structure

Sequence of a chain of amino acids

Secondary protein structure

Hydrogen bonding of the peptide backbon ecauses the amino acids to fold into a repeating pattern

Tertiary protein structure

Three-dimensional folding pattern of a protein due to side chain interactions

Quarternary protein structures

Protein consisting of more than one amino acid chain

Amino acid

Monomers that link together to form larger polymers known as proteins

Components of an amino acid

Distinctive “R” group

Central carbon

Amino group

Carboxyl group

Hydrogen atom

Enzymes

Catalyze chemical reactions

Defensive proteins

Protect against disease

Storage proteins

Store amino acids

Transport proteins

Transport substances

Hormones

Coordinate organismal responses

Receptor proteins

Receive signals from outside cell

Motor proteins

Function in cell movement

Structural proteins

Provide structural support

Triglycerides

AKA triacylglycerols (fats or oils): glycerol + three fatty acids

Function: important energy source

Phospholipids

Glycerol + phosphate group + two fatty acids

Function: Lipid bilayer of membranes (hydrophilic heads, hydrophobic tails)

Hypothesis

Proposed explanation for an observed phenomenon (answer to the question)

Prediction

Statement of an outcome that is expected if hypothesis is correct

Which is NOT a reason carbon is essential for life?

Carbon is chemically inert and rarely reacts with other elements

False

True or false, by mass, carbon is the most common element making up living organisms

Which is a possible base composition for double-stranded DNA?

%A: 5 %G: 45 %C: 45 %T: 5 %U: 0

If the percentage of adenine in double-stranded DNA is 30%, what is the percentage of guanine, thymine, and cytosine

G = 20% T = 30% C = 20%

If the percentage of adenine in single-stranded DNA is 30%, what is the percentage of guanine, thymine, and cytosine?

There is insufficient information to answer the question (percentages that equal each other apply to DOUBLE stranded; also does not apply to RNA)

Dehydration reaction

What type of reaction is involved in making polymers from monomers?

Which of the following describes a peptide bond?

A covalent bond between two amino acids

Disulfide bridge

Which bond can form between two cysteine side chains and help stabilize protein structure?

Secondary

The alpha helix and beta-pleated sheet are part of which protein structure?

Are not true polymers

Lipids differ from other large biological molecules because they:

Ester linkage

Forms between a carboxyl group of a fatty acid and a hydroxyl group of glycerol

Double bonds create kinks in the chain

WHy do unsaturated fatty acids bend in their hydrocarbon chains?

They have hydrophilic heads and hydrophobic tails

WHy are phospholipids well suited for cell membranes?

Water

What do lipids mix poorly with?

They tend to dissolve in water easily

Saturated fats have all of the following characteristics except for what?

Polar heads interact with water, the nonpolar tails do not

Which of the following describes the interaction of water molecules with phospholipids

Response to light

Which of the following is NOT a fundamental characteristic required to classify an entity as a living organism?

Inductive reasoning

Moving from a series of specific, isolated experimental observations to formulate a broad, comprehensive biological principle relies primarily on which type of logic?

Cannot measure phenomena that are unobservable

What is considered a limitation of the scientific method?

-1

An ion that consists of 7 protons, 6 neutrons, and 8 electrons has a et charge of…

Each hydrogen atom has a partial positive charge; the nitrogen atom has a partial negative charge

Nitrogen is more electronegative than hydrogen. Which of the following is a correct statement about the atoms in ammonia?

Energy storage and release

Carbohydrates are used in our bodies mainly for…

Monosaccharides

Which molecules are directly jined by a glycosidic linkage?

5’ to 3’

DNA sequences are conventionally read in which direction?

They allow complementary bases within a single RNA strand to pair and form stem structures

How do hydrogen bonds contribute to RNA second structure

Saturated fatty acids

Only have single bonds, solid at room temperature, results in the maximum number of hydrogen atoms

Unsaturated fatty acids

One or more double bonds

One fewer hydrogen for each double bond

Liquid at room temperature

Steroids

Lipids characterized by a carbon skeleton consisting of four fused rings

Amphipathic

A molecule having both a hydrophobic region and a hydrophilic region

Which types of amino acids interact favorably with water?

+ charged, - charged, polar