BIO 1912 Mid Term 1

Lectures 1-9

The decay of what carbon isotope is used in radiocarbon dating?

Carbon-14

What is a covalent bond?

Sharing of a pair of valence electrons by 2 atoms

What is a polar covalent bond?

1 atom is more electronegative, electrons are not shared equally, creates a slight charge

What is cohesion?

the binding together of alike molecules, primarily driven by hydrogen bonding between water molecules

Why is water the universal solvent?

its polar molecular structure allows it to dissolve more substances than any other liquid. An H2O molecule has a positively charged hydrogen side and a negatively charged oxygen side, enabling it to pull apart ionic compounds and attract polar molecules, such as salts, sugars, and minerals.

What is an aqueous solution?

Solution where water is the solvent

What is an acid?

A substance with a high concentration of hydrogen

Which of these materials can be studied with radiocarbon dating ( bones, quartz crystals, charcoal, clay, water)?

Bones, charcol

What is difference between two atoms of the same element that are different isotopes?

The number of neutrons

When water disassociates what molecules does it form?

Hydronium (H3O+) and hydorxide (OH-)

For two atoms joined in a polar covalent bond, what is the term used for the property of the shared electrons being drawn closer to one atom than the other?

electronegativity

What does ATP stand for?

Adenosine triphosphate

In 1953 Stanley Miller set up an experiment to mimic the conditions thought to exist on early earth. In addition to heat, what was the energy source in this experiment?

electricity or sparks

A molecular compound that is attracted to water molecules is _____.

Hydrophilic

A molecular compound that is repelled by water molecules is _____.

Hydrophobic

Which one of these kinds of functions are proteins NOT important for? energy storage, enzymatic, cell structure, hormonal, cell movement

energy storage

Which type of polymer, fatty acids or polysaccharides, have large numbers of hydroxyl (-OH) groups?

polysaccharides

At what University were the first structures of large molecules discovered using X-ray crystallography?

Cambridge

What two general kinds of long molecules (polymers) where among the first to have their structures revealed by x-ray crystallography?

DNA and proteins

What molecule does DNA code for, that is then used to code for proteins?

RNA

DNA consists of 4 types of nucleotide bases, labeled A, C, G and T. What was the base pairing rule discovered by Watson and Crick?

A = T, C = G

What was the main method used to discover the 3D structure of DNA?

x-ray crystallography

Chloroplasts do this reaction 6CO 2 + 6H 2O → C6H 12O 6 + 6O 2 . What organelle does the reverse reaction?

Mitochondria

Which one or more of these are NOT part of the endomembrane system of a eukaryotic cell? ( golgi, ribosomes, nuclear envelope, endoplasmic reticulum, mitochondria)

ribosomes, mitochondria

What kind of prokaryote was the early eukaryote cell that engulfed the other one most closely related to?

archea

About how long ago (in years) did eukaryote cells evolve?

2-3 billion years

What are the properties of water that help facilitate life?

cohesion and adhesion, ability to moderate temperature, expansion upon freezing, versatility as a solvent

Why is carbon the ‘building block for life’?

it can form 4 covalent bonds and it is very common

What is polymerization?

process by which cells make polymers, facilitated by enzymes

What is a condensation reaction?

process of connecting monomers or (monomers to a polymer)

What is a dehydration reaction?

2 molecules become covalently bonded with the removal of a water molecule

What is hydrolysis?

addition of water molecule to disassemble polymers (the reverse of a dehydration reaction)

What is a monosaccharide?

a simple sugar

What is a disaccharide?

two monosaccharides joined by a covalent bond

What is a glycosidic linkage?

a covalent bond between monosaccharides formed by dehydration reaction

What is the primary stored form of glucose in animals?

Glycogen

What is the primary stored form of glucose in plants?

Starch

What makes cellulose strong?

linear arrangement of beta glucose units, which form long, straight, non-branching chains. These chains line up into microfibrils.

Describe a saturated fat:

solid at room temperature, saturated with hydrogen, fatty acids stacked

Describe an unsaturated fat:

liquid at room temperature, missing hydrogen, kinks in fatty acid tails, fatty acids not stacked

What is a phospholipid constructed of?

Glycerol (hydrophilic head) and 2 fatty-acid tails (hydrophobic)

What is a polypeptide?

An amino acid polymer

How many amino acids are there?

20

What type of bond joins amino acids to form proteins?

a polypeptide bond

What formula determines the number of polymer combinations?

K^n

What is glycolysis?

breaking down of glucose

What is the enzyme that breaks starch into simple sugars?

amylase

What is the structural polysaccharide of plants?

cellulose

What is the structural polysaccharide of animals?

chitin

What is a trans fat?

random hydrogenation of unsaturated fats, solid at room temp

What is an example of a steroid?

cholesterol

What differentiates different amino acids?

the r group

What is the monomer of nucleic acids?

nucleotide

What are the two types of nucleic acids?

DNA and RNA

What is a nucleotide made of?

Phosphate group, pentose sugar and nitrogenous base

What is a phosphodiester linkage?

Makes the sugar-phosphate backbone of nucleic acids

What is different about RNA molecules from DNA?

RNA are single stranded (base pairing can occur), adenine pairs with uracil, variable in shape

What is the reverse compliment of 5’ATTGA 3’ ?

5’ TCAAT 3’

DNA strands are anti parallel and run ____ to _____.

5’ to 3’

Each chromosome contains 1 ____ molecule.

long DNA

How many chromosomes do humans have?

46

How many chromosomes do human sex cells have?

23

What is a ribosome?

A protein factory, non membrane bound

Cells with high rates of protein synthesis have a lot of _______.

ribosomes

What makes up the endomembrane system?

nuclear envelope, endoplasmic reticulum (ER), Golgi apparatus, lysosomes, vesicles, vacuoles, and the plasma membrane

What is the endoplasmic reticulum?

biosynthetic factory with MANY functions

What is the function of the golgi aparatus?

shipping and receiving

What are lysosomes?

digestive vacuoles filled with hydrolyzing enzymes

What is phagocytosis?

When a unicellular organism engulfs another unicellular organism

What is a vacuole?

storage and maintenance compartments

What reaction do mitochondria carry out?

cellular respiration

What reaction do chloroplasts carry out?

photosynthesis

What is the endosymbiotic theory?

mitochondria and chloroplasts originated as free-living prokaryotic bacteria that were engulfed by a larger host cell, leading to eukaryotic cells

What are the functions of the plasma membrane?

structural integrity, communication, growth and division, selective barrier

What does amphipathic mean?

hydrophobic and hydrophilic ends (ex. phospholipid)

Why do deep sea organisms have more unsaturated fatty acids in their plasma membranes?

To make sure their plasma membranes stay fluid at deep sea pressures

What is passive transport?

No energy required, ex. diffusion or facilitated diffusion

What is active transport?

chemical or electrical energy required to move solutes against concentration gradient

What are the two main types of transport proteins?

channel and carrier

What is the electrochemical gradient?

chemical gradient and concentration gradient

What is ectocytosis?

cells release membrane-bound vesicles

What is endocytosis?

cells absorb molecules/nutrients by engulfing them

What is tonicity?

the ability of a solution to cause a cell to loose or gain water

What is a hypertonic solution?

a solution with a higher concentration of solutes

What is a hypotonic solution?

a solution with a lower concentration of solutes

What is metabolism?

all of an organisms chemical reactions

What is a metabolic pathway?

the road map/specific steps for metabolism

What is a catabolic pathway?

metabolic pathway that releases energy by breaking down complex molecules into smaller molecules

What is an anabolic pathway?

metabolic pathway that consumes energy to make complex molecules from small molecules

What is thermodynamics?

the study of energy transformations that occur in a collection of matter

What is the 1st Law of Thermodynamics?

Energy can be transferred and transformed but cannot be created or destroyed

What is the 2nd Law of Thermodynamics?

Every energy transfer or transformation increases the entropy of the universe

What is entropy?

a measure of molecular disorder, randomness, or the unavailability of energy to do useful work within a system, always increasing

Organisms have ____(high/low) entropy.

low

What is free energy?

the portion of a systems energy that can perform work when temperature = pressure in a system, represented as ΔG

If ΔG is negative (-ΔG) what does this mean?

a chemical reaction or physical process is spontaneous, thermodynamically favorable, and occurs in the forward direction without requiring external energy

What is an exergonic reaction?

a spontaneous chemical process that releases free energy

What is an endergonic reaction?

a non-spontaneous chemical process that requires an input of energy from its surroundings to proceed

What is never at equilibrium?

metabolism/cells

What is energycoupling?

use of exergonic process to drive an endergonic one