Bio exam a real

carbohydrates

Fuels for organism, structural components of cell membranes inucleic acids, bacterial and plant cell walls, carbon source

carbohydrates

Monosaccharide has a simple skeleton made up of 3 to 8 carbons, each carbon atom except one is linked to a hydroxyl group, the remains is linked to an oxygen forming a carbonyl group

Isomer

Sugars with the same chemical formula but different structures

Synthesis

Requires both enzymes and a source of energy

Breakdown

Involves an enzyme on a biological timescale

Disaccharides, polysaccharides

Monosaccharides are linked together to form _____ or ______ through a reaction called dehydration synthesis (or a condensation reaction), which releases a molecule of water

Glycosidic acid bond

Two monosaccharides are usually linked by this

Maltose

The disaccharides formed from two glucose molecules are _____

Surose

A common table sugar

Polysaccharide

A large carbohydrate made from many monosaccharides

Starch

What plant energy-storage polysaccharide is made of \(\alpha \)-glucose, forms a helical structure, and features some branching?

Glycogen

Animals store excess glucose as _______, a highly branched polysaccharide. (Animals, energy storage , highly branched, extensive branching)

Cellulose

Which structural polysaccharide in plants is unbranched, straight, and composed of glucose monomers?

Protein

______ are polymers made from amino acids, one or more polypeptide chains that perform a function

Amino acid

Monomer/building block of proteins

Peptide bond

Covalent bond connecting amino acids

Peptide bond

Covalent bond connecting amino acids

Polypeptide

When many amino acids are joined together, they form a ______

Dehydration synthesis

Removes water to build a bond/polymer

Hydrolysis

Adds water to break bond

dipeptide

A dehydration synthesis (or condensation) reaction links two amino acids together to form a ______ and releases a molecule of water. Peptide bond formation.

R

___ represents the side chain. The ___ group is what makes one amino acid different from another,

Different R groups

Different chemical properties to different protein behavior

Nonpolar

Hydrophobic

Polar

Hydrophilic

Basic

Positively charged

Acidic

Negatively charged

Denaturalization

Loss/change of normal protein structure I temperature, pH, chemical environment

Nucleic acid

DNA: deoxyribonucleic acid, RNA:ribonucleic acid

Nucleotide

Nitrogenous base, five carbon sugar, phosphate sugar

Nucleoside

Base+ sugar

A,t,g,c

Nitrogenous bases of DNA

A,u,g,c

Nitrogenous bases of RNA

Purines

Two rings, adenine and guanine

Pyridines

One ring, cytosine, thymine, uracil

DNA

Stores genetic info , double stranded

macromolecules

Carbohydrates, lipids, proteins , nucleic acids

build, break down

Dehydration synthesis and hydrolysis are opposing chemical reactions that ____ and ______ biological macromolecules

empirical formula of carbohydrate

(CH₂O)ₙ

aldose, ketose

Based on the location of the carbonyl group, a monosaccharide with the carbonyl at the end of the chain is called an ___________, while one with an internal carbonyl is called a ___________.

below, above

In α-glucose, the C1 hydroxyl points ____ the ring plane. In β-glucose, it points _____.

Starch, Cellulose

____ is made of α-glucose, with 1-4 links (plus 1-6 branches in amylopectin), and coils into a helix. ____ is made of β-glucose, with each monomer flipped 180° relative to its neighbor, giving straight, unbranched chains.

Cellulose

_____ chains are straight, so many chains line up in parallel. Extensive hydrogen bonding between them bundles them into rigid microfibrils. This affects the solubility of a macromolecule in water

polarity

_____, which comes from hydrophilic groups (-OH, charged groups) that can hydrogen-bond with water. Solubility drops as the proportion of nonpolar hydrocarbon (C-H) increases. Molecule size also matters. affect the solubility of a macromolecule in water

triglyceride

One glycerol and three fatty acids, joined by ester linkages, form a _______

Fatty acid

A single molecule with a carboxylic acid group and a long hydrocarbon tail is a _____

Hexose: C6H12O6. Triose: C3H6O3

Monosaccharides are classified by their number of carbons. All monosaccharides of a specific carbon number have the same chemical formula. What is the formula for all hexose sugars?  __________________            All triose sugars ________________?   

Cellulose

Has 1–4 β glucose linkages

Glycogen

A storage polysaccharide produced by vertebrates that is stored
​​​in the liver

Glucose

Two monomers of this molecule form maltose

Fructose

Glucose +                             form sucrose

Fructose

Monosaccharide commonly called “fruit sugar”

Lactose

“Milk sugar”

Chitin

Structural polysaccharide that gives cockroaches their crunch

Cellulose

______ is the primary structural polysaccharide that comprises plant cell walls

enzymes, structure, transport, defense, signaling, movement, storage

main functions of protein

Amino acids

___ have a central carbon bonded to an amino group, a carboxyl group, an H and a r group

protein

A _____ is a chain of amino acids with a specific three-dimensional shape

R

___ is the variable side chain that gives each amino acid its identity (size, polarity, charge). There are 20 different __ groups, so 20 amino acids.

Four levels of protein structure

Primary, secondary, tertiary, quaternary

Primary

The linear sequence of amino acids joined by peptide bonds is called the _______ structure of a protein

Secondary

What level of protein structure is characterized by local folding into alpha helices and beta pleated sheets, stabilized by hydrogen bonds between backbone atoms?

Tertiary

The overall 3D shape of a single polypeptide chain is its ____ strutcture. , from r group interactions hydrophobic interactions , H bonds , ionic bonds, disulfide bridges)

Quaternary

Two or more polypeptide chains assembled into a functional protein represent the ________ structure of a protein

phosphate group, a pentose sugar, nitrogenous base

three components of a nucleotide

nucleotides

The monomers that link to produce a nucleic acid are called ___

Adenine, guanine, cytosine, thymine.

bases found in DNA

Adenine, guanine, cytosine, uracil

nitrogenous bases are found in RNA

ribose

____ a simple five-carbon sugar (pentose) with the chemical formula C₅H₁₀O₅ that serves as a fundamental building block for genetic material and cellular energy. [1, 2, 3]. Has an -OH on the 2′ carbon

antiparallel strands

The two strands run in opposite directions: one runs 5′→3′ while its partner runs 3′→5′.

free energy

the portion of a system’s energy available to do work. Its symbol is G (Gibbs free energy).

change in free energy

ΔG = G(final) − G(initial)

catabolic and anabolic

What are the two types of reactions in metabolic pathways?

spontaneous process

A process that occurs without a continuous input of energy. It does not mean fast; it only means energetically favorable (ΔG < 0).

negative

Once we know the value of ΔG for a reaction we can use it to predict whether it will be spontaneous. For an exergonic reaction, is ΔG negative or positive?

energy coupling

Using the energy released by an exergonic reaction (usually ATP hydrolysis) to drive an endergonic reaction that would not otherwise occur.

released

When the terminal phosphate bond is broken, a molecule of inorganic phosphate Pi is formed, and energy is -------------------.

catalyst

A substance that speeds up a chemical reaction without being consumed by it.

enzymes

_____ lower the activation energy barrier. They bind substrates at the active site, hold them in an orientation that favors reaction, strain bonds, and/or provide a favorable microenvironment. They don’t change ΔG or the equilibrium, only how fast it is reached. (speed up metabolic reactions)

activation energy

The initial energy input needed to start a reaction (to break bonds in the reactants and reach the transition state), symbol EA.

enzyme

a protein catalyst that speeds up a specific reaction.

substrate

the reactant the enzyme acts on.

active site

the region of the enzyme where the substrate binds and the reaction occurs.

products

the molecules released after the reaction.

protein, enzyme

An enzyme’s 3D shape (tertiary/quaternary structure) is determined by its amino acid sequence. That shape creates an active site with a specific geometry and R-group chemistry (charge, polarity) that fits only certain substrates. Changing the sequence or denaturing the protein (heat, pH) alters the shape and destroys specificity and activity. So, ____ structure is involved in ____.

spontaneous, exergonic

A change in Gibbs free energy of Δ G < 0 means the process is ______(thermodynamically favored) in the forward direction and ______(releases free energy)

capacity to do work

systems with high free energy can do more work. A reaction that releases free energy can be harnessed to do work.

stability

high G means unstable (tends to change); low G means stable, at equilibrium.

exergonic

ΔG negative, releases energy, spontaneous.

endergonic

ΔG positive, absorbs energy, non-spontaneous.

catabolic

break down complex molecules into simpler ones, releasing energy (e.g., cellular respiration).

Anabolic

build complex molecules from simpler ones, requiring energy input (consumes ATP) (e.g., protein synthesis, photosynthesis).

induced fit

when the substrate binds, the active site changes shape slightly to fit the substrate more snugly, like a handshake rather than a rigid lock and key. This tightens the fit and helps catalysis. In the figure (referenced as question 22, which isn’t in this guide), it would be the step where the enzyme’s active site changes shape as the substrate enters.

triglyceride

A glycerol molecule combined with three fatty acids forms a ______

Phospholipids

glycerol + 2 fatty acids + a phosphate head. They form cell membranes.

Steroids

four fused carbon rings. Cholesterol regulates membrane fluidity, and these are also hormone precursors.

Lipids

____are the broad class of hydrophobic or amphipathic (partially water-loving) biological macromolecules that includes fats, phospholipids, steroids, and waxes

Deoxyribose

______ (found in DNA) has only a hydrogen atom (–H) at that same 2' carbon position, meaning it has exactly one fewer oxygen atom

Pepsin, stomach

____, found in the ____ (gastric juice), where the pH is about 2. It digests proteins.

competitive inhibitors, noncompetitive inhibitors

____ bind the active site and block the substrate; _____ bind elsewhere and change the enzyme’s shape, reducing activity.