BIO 101

Question 1

What is all matter composed of

Question 2

What is the Bohr model?

Question 3

Protons have a

Answer 3

positive charge (defined as +1 unit of charge)

Question 4

Electrons have a

Answer 4

negative charge (defined as -1 unit of charge)

Question 5

Neutrons have

Answer 5

zero charge

Question 6

What is the mass of protons, neutrons, electrons?

Answer 6

● Mass of one proton or one neutron = atomic mass unit (amu) or 1 dalton, or 1.7 × 10–24 grams.
● Mass of one electron = 9 × 10–28— (0.0005 Da) , usually ignored

Question 7

What is an element?

Answer 7

It is a pure substance containing only one kind of atom
● Elements are arranged in the periodic table.
● Elements in the same vertical columns have similar properties.

Question 8

About 98% of the mass of most living organisms is composed of these six elements:

Answer 8

1. carbon
2. hydrogen
3. nitrogen
4. oxygen
5. phosphorus
6. sulfur

Question 9

How do I find the number of protons?

Answer 9

The number of protons in the nucleus of an atom is called its atomic number: the atoms of a particular element all have the same number of protons. the atoms of different elements have different numbers of protons.
Atomic number is the 1st line in the element square on the periodic table.

Question 10

What is a mass number?

Answer 10

It is the sum of the numbers of protons and neutrons present in the nucleus of an atom.

Question 11

What are Isotopes?

Answer 11

Isotopes are versions of the same element. They have the same number of protons and electrons as the element but different mass numbers and number of neutrons. See picture 1

Question 12

What are radioisotopes?

Answer 12

They are radioactive isotopes. They are unstable, they give off energy in the form of alpha, beta, and gamma radiation from the nucleus.

Question 13

What determines how atoms will interact?

Answer 13

The number of electrons in the outermost shell of a particular atom determines how atoms will interact.

Question 14

What describes the location of electrons in an atom?

Answer 14

Orbitals.

Question 15

What is a chemical bond?

Answer 15

attractive force that links atoms together to form molecules. There are several different kinds such as :
● Covalent bonds, Ionic bonds, and Hydrogen bonds.

Question 16

What are Covalent bonds?

Question 17

What are Ionic bonds?

Question 18

What are Hydrogen bonds?

Question 19

What is Electronegativity?

Answer 19

Electronegativity is a measure of an atom’s ability to attract shared electrons to itself. On the periodic table, electronegativity generally increases as you move from left to right across a period and decreases as you move down a group. It depends on the number of positive charges (protons) and the distance between the nucleus and electrons.

Question 20

What four molecules are characteristic of living things?

Answer 20

1. Proteins
2. Carbohydrates
3. Lipids
4. Nucleic acids

Question 21

What are monomers? And polymers? And how are they connected?

Answer 21

Monomers are small molecules, mostly organic, that can join with other similar molecules to form very large molecules, or polymers.
A polymer is any of a class of natural or synthetic substances composed of very large molecules, called macromolecules, which are multiples of simpler chemical units called monomers. Polymers make up many of the materials in living organisms and are the basis of many minerals and man-made materials.

Question 22

What are macromolecules?

Answer 22

Polymers with molecular weights >1000 g/mol.

Question 23

What are Functional groups?

Answer 23

: groups of atoms with specific chemical properties and consistent behavior; it confers those properties when attached to large molecules.
One macromolecule can contain many different functional groups— determines shape and function.

Question 24

What are Isomers?

Answer 24

Molecules with the same chemical formula, but atoms are arranged differently
Structural isomers: differ in how their atoms are joined together
Optical isomers are two compounds which contain the same number and kinds of atoms, and bonds (i.e., the connectivity between atoms is the same), and different spatial arrangements of the atoms, but which have non-superimposable mirror images.

Question 25

How are Polymers formed and broken down?

Answer 25

Polymers are formed in condensation reactions. Monomers are joined by covalent bonds. A water is removed—also called dehydration reaction.
● Polymers are broken down into monomers in hydrolysis reactions. (hydro, “water”; lysis, “break”)

Question 26

What are Proteins?

Answer 26

Proteins are large, complex molecules that play many critical roles in the body. They do most of the work in cells and are required for the structure, function, and regulation of the body’s tissues and organs. Proteins are made from 20 different amino acids (monomeric units).

Question 27

Proteins functions include:

Answer 27

o Structural support: such as collagen
o Protection: such as antibodies
o Transport: such as Hemoglobin
o Catalysis: such as enzymes
o Regulation: such as hormones, and insulin
o Response: such as receptor proteins
o Storage: proteins that store amino acids for later use
o Genetic regulation: proteins that control when and how a gene is expressed

Question 28

What do Proteins consist of?

Answer 28

● Proteins consists of polypeptide chains: single, unbranched (linear) chain of covalently linked amino acids.
● Variation in the sequence of amino acids present in polypeptide chains is the source of diversity in protein structure and function.

Question 29

What are Amino acids?

Answer 29

Amino acids are molecules that combine to form proteins. Amino acids and proteins are the building blocks of life. When proteins are digested or broken down, amino acids are left. Amino acids exist in two isomeric forms:
D-amino acids (dextro, “right”)
L-amino acids (levo, “left”) —this form is found in most organisms
Amino acids can be grouped based on side chains.

Question 30

How do Amino acids form Proteins?

Answer 30

Amino acids bond together covalently in condensation reactions by peptide bonds to form the polypeptide chain. A peptide bond is relatively inflexible limiting the folding of the polypeptide
chain.

Question 31

What is the primary structure?

What is the secondary structure?

Answer 31

● The primary structure of a protein is the sequence of amino acids. It is established by covalent bonds.
● The sequence determines secondary and tertiary structure—how the protein is folded.
● Secondary structure: two basic types
➢ αhelix—right handedcoilresultingfromhydrogenbonding;commoninfibrous
structural proteins
➢ β pleated sheet—two or more polypeptide chains are aligned

Question 32

What is tertiary structure?

Answer 32

Bending and folding results in a macromolecule with specific three-dimensional shape.
● Tertiary structure is determined by interactions of R-groups:
➢ Disulfide bonds: between cysteine side chains
➢ Aggregation of hydrophobic side chains in interior of protein
➢ Van der Waals forces: between hydrophobic side chains
➢ Ionic bonds: form salt bridges between positively and negatively charged side chains
➢ Hydrogen bonds stabilise folds in proteins
● When a protein is heated, heat will disrupt weak interactions in secondary and tertiary structures, but it can return to its normal tertiary structure when cooled (so unique shape of protein is in its primary structure).

Question 33

What is a Quaternary structure?

Answer 33

results from the interaction of two or more polypeptide chains (subunits) by hydrophobic interactions, van der Waals forces, ionic bonds, and hydrogen bonds

Question 34

What is Denaturation? And what is Chaperones?

Answer 34

● Denaturation: irreversible loss of 3- dimensional structure and thus function of the protein
● Proteins can sometimes bind to the wrong ligands.
● Chaperones are proteins that help prevent this. They surround new or denatured proteins. An example: are heat shock proteins.

Question 35

What are Carbohydrates?

Answer 35

The compounds of carbon, hydrogen and oxygen which provide energy for our body are called carbohydrates.
They have 2 major roles: as an Energy source, and as Carbon skeletons that can be arranged to form new molecules.
There are 4 important categories of carbohydrates:
➢ Monosaccharides: simple sugars
➢ Disaccharides: two simple sugars linked by covalent bonds
➢ Oligosaccharides: three to 20 monosaccharides
➢ Polysaccharides: hundreds or thousands of monosaccharides—starch, glycogen, cellulose
● The general formula for carbohydrates: CH2O (1:2:1 ratio)

Question 36

What can carbohydrates be modified with?

Answer 36

Carbohydrates can be modified by the addition of functional groups.
➢ Sugar phosphates: phosphate group added to one or more of –OH
sites
➢ Amino sugars: amino group is substituted for –OH group

Question 37

What are Lipids?

Answer 37

A lipid is any of various organic compounds that are insoluble in water. They are non polar hydrocarbons.
● Roles of lipids:
➢ Fats and oils—energy storage
➢ Phospholipids—cell membranes
➢ Carotenoids and chlorophylls—capture light energy in plants
➢ Steroids—regulatory roles as hormones and vitamins
➢ Fats— thermal insulation in animals
➢ Lipid nerve coatings —act as electrical insulation
➢ Oils and waxes— repel water, prevent drying on the surfaces of skin, fur, and feathers

Question 38

What are Triglycerides?

Answer 38

Called simple lipids—made of three fatty acids and 1 glycerol. If solid at room temperature they are called fats, liquid at room temperature they are called oils.

Question 39

What are saturated and unsaturated fatty acids?

Answer 39

● Saturated fatty acids: no double bonds between carbons—it is saturated with hydrogen atoms.
● Unsaturated fatty acids: some double bonds in carbon chain. ➢ monounsaturated: one double bond
➢ polyunsaturated: more than one
● Animal fats tend to be saturated—packed together tightly—solid at room temperature.
● Plant oils tend to be unsaturated—the “kinks” prevent packing—liquid at room temperature.

Question 40

What are Phospholipids?

Answer 40

Fatty acids bound to glycerol, a phosphate group replaces one fatty acid. (amphipathic properties)
● Phosphate group is hydrophilic—the “head”
● “Tails” are fatty acid chains—hydrophobic

Question 41

What are Nucleotides?

Answer 41

A nucleotide is the basic building block of nucleic acids. RNA and DNA are polymers made of long chains of nucleotides. They are specialised for storage, transmission, and use of genetic information.
Nucleic acids are polymers—the monomeric units are nucleotides.
Nucleosides: molecules consisting of a pentose sugar and nitrogenous base, but no phosphate group.
● Other roles for nucleotides:
➢ ATP—energy transducer in biochemical reactions
➢ GTP—energy source in protein synthesis
➢ cAMP—essential to the action of hormones and transmission of information in the nervous system

Question 42

RNA and DNA bases?

Answer 42

● DNA bases: adenine (A), cytosine (C), guanine (G), and thymine (T)
● Complementary base pairing:
A—T
C—G
● Purines pair with pyrimidines by hydrogen bonding.
● Instead of thymine, RNA uses the base uracil (U).

Question 43

DNA and RNA extra information

Answer 43

• DNA is an informational molecule: information is encoded in the sequences of bases. DNA carries hereditary information between generations.
• RNA uses the information to determine the sequence of amino acids in proteins.
• The two strands of a DNA molecule form a double helix.
• All DNA molecules have the same structure—variation is in the sequence of base pairs.
• Determining the sequence of bases helps reveal evolutionary relationships.

Question 44

What surrounds cells?

Answer 44

. .
● All cells are surrounded by a membrane: the plasma membrane is made of a phospholipid bilayer.
● The plasma membrane:
Allows cells to maintain constant internal environment (homeostasis).
Is a selectively permeable barrier.
Is important in communication and receiving signals from environment.
Often has proteins for binding with adjacent cells (structural role).

Question 45

What are the 2 types of cells?

Answer 45

Cells are of two types: eukaryotic, which contain a nucleus, and prokaryotic cells, which do not have a nucleus, but a nucleoid region is still present. Eukaryotic cells have membrane-enclosed compartments called organelles, with specific functions.
Prokaryotes are single-celled organisms, while eukaryotes can be either single-celled or multicellular.
● Prokaryotes are small, can live in extreme environments, and do not have internal compartments.
Prokaryotic cells share certain features:
Are enclosed by a plasma membrane.
The DNA is contained in the nucleoid.

Question 46

What is a cytoplasm?

Answer 46

Cytoplasm is the gelatinous liquid that fills the inside of a cell. It is composed of water, salts, and various organic molecules. Some intracellular organelles, such the nucleus and mitochondria, are enclosed by membranes that separate them from the cytoplasm.
Cytoplasm consists of cytosol (water and dissolved material) and ribosomes—site of protein synthesis, made of proteins and RNA.

Question 47

the structure of animal and plant cells

Question 48

Organelles and nucleus

Answer 48

Organelles are specialized structures that perform various jobs inside cells.
The nucleus is a double-membraned organelle that contains the genetic material and other instructions required for cellular processes. It is exclusively found in eukaryotic cells and is also one of the largest organelles.
● Contains the DNA
● Site of DNA replication
● The nucleolus begins assembly of ribosomes
● The nucleus is surrounded by two membranes—the nuclear envelope.
● Nuclear pores in the envelope control passage of molecules. Each pore is surrounded by a complex of 8 large proteins arranged in an octagon. Ions and small molecules freely diffuse through. Large molecules such as proteins need a signal (nuclear localization sequence)—a certain sequence of amino acids— to pass through.

Answer 49

● Inside the nucleus, DNA combines with proteins to form chromatin. Before cell division, chromatin aggregates to form chromosomes.
● Surrounding the chromatin are water and dissolved substances called nucleoplasm.
● Within the nucleoplasm, a network of structural proteins called nuclear matrix organises the chromatin.
● Chromatin is attached to the nuclear lamina, formed by the polymerisation of protein lamins into filaments. Nuclear lamina maintains shape of the nucleus.
Picture of nucleoplasm

Question 50

What are Ribosomes?

Answer 50

Ribosomes are also organelles
● Ribosomes—sites of protein synthesis.
Occur in both prokaryotic and eukaryotic cells.
● In eukaryotes, ribosomes are free in the cytoplasm, attached to the endoplasmic reticulum, or inside mitochondria and chloroplasts.
● Ribosomes consist of two different sized subunits (somewhat larger in eukaryotic cells) and a special type of RNA called ribosomal RNA (rRNA), to which more than 50 different protein molecules are noncovalently bound.

Question 51

Endomembrane system: Endoplasmic reticulum

Answer 51

The outer membrane of the nuclear envelope is continuous with the endomembrane system.
● Endoplasmic reticulum (ER): a network of interconnected membranes—large surface area
Rough endoplasmic reticulum (RER): ribosomes are attached
RER receives newly made proteins—they enter the interior compartment, lumen,
and can be modified and transported.
Smooth endoplasmic reticulum (SER): more tubular, no ribosomes
● Chemically modifies small molecules such as drugs and pesticides (making them more polar so they can be easily removed).
● Hydrolysis of glycogen in animal cells
● Synthesis of lipids and steroids

Question 52

Golgi apparatus:

Answer 52

A Golgi body, also known as a Golgi apparatus, is a cell organelle that helps process and package proteins and lipid molecules, especially proteins destined to be exported from the cell. Is an organelle found in most eukaryotic cells
● Stacked, flat, membrane-bound sacks called cisternae.
● Receives proteins from the ER—can further modify them.
● Concentrates, packages, sorts proteins before sending them to their destinations.
● In plant cells, some polysaccharides for cell walls are synthesized.

Question 53

Mitochondria

Answer 53

Organelles that transform energy: Mitochondria and Plastids

• In the mitochondria, energy in fuel molecules of sugars, fats and amino acids is transformed to the bonds of energy-rich ATP: cellular respiration.
• ATP potential energy can be transformed into kinetic energy (energy of movement / work) within the cell.
• Cells that require a lot of energy have a lot of mitochondria.
• The inner membrane of a mitochondrion folds inward (cristae)—creating a large surface area for proteins that participate in cellular respiration reactions.
• The mitochondrial matrix contains enzymes, as well as its own DNA and ribosomes.
• Their DNA is necessary for making some of the proteins of the mitochondria. Other genes for making proteins of the mitochondria are located in the nuclear DNA.

Question 54

Chloroplasts

Answer 54

● Plastids occur only in plants and some protists.
● Chloroplasts: contain the green pigment chlorophyll and are sites of photosynthesis—light energy is converted to the energy of chemical bonds.
Chloroplasts have a double membrane as well as internal membranes.
The internal membrane forms thylakoids. The membranes of the thylakoids contain chlorophyll and other pigments for harvesting light energy for photosynthesis.
● Grana—stacks of thylakoids—made of circular compartments of the inner membrane.
● Stroma—fluid in which grana are suspended. The stroma contains DNA and ribosomes for making some of their own proteins.
● Like mitochondria, some of the genes for making chloroplast proteins are in the nucleus of the cell.