Biology 101 Midterm #1 Fall 2026

What are the two Peripheral proteins that belong to the Interior Protein Network? What do they do?

Spectrins - Anchoring molecules that act as scaffolding between cell membrane and cytoskeleton

Clathrins - Forms a protein coat inside the cell membrane, pinches, and forms a vesicle during endocytosis

What are Integral Proteins? What do they do?

Integral proteins - Protein channels/pumps along the plasma membrane that facilitate movement of materials in and out of the cell (as well as other functions)

What are the 6 types of Integral Proteins?

1) Transporters of material in and out of the cell

2) Enzymes that catalyze reactions at the cell membrane

3) Cell-Surface receptors that respond to hormones

4) Cell-Surface Identity markers

5) Cell to cell adhesion proteins

6) Structural proteins that attach to the cytoskeleton

What are pores and how do they form?

Pores are openings in the cell membrane, such as protein channels and carriers.

Formed by cylinder-shaped arrangement of beta sheets that create an opening in the membrane

What is passive transport and what are the 3 types?

Passive Transport - Movement of molecules across the cell membrane with no energy

1) Diffusion - Molecules move high conc. to low conc.

2) Facilitated diffusion - Molecules that are too large or too polar to diffuse move through protein channels

3) Osmosis - Diffusion of water across a membrane towards higher conc. of solute

What are the 2 types of proteins used in facilitated diffusion?

1) Ion channels - Passage of ions through the membrane. Gated channels open/close in response to a stimulus.

2) Carrier Proteins - For movement across the membrane that only requires a difference in conc. gradient

What is osmotic pressure and the three relative conc. states?

Osmotic pressure - Pressure required to stop osmosis

1) Hypertonic - Conc. of solute is higher than it’s environment

2) Hypotonic - Conc. of solute is lower than its environment

3) Isotonic - Has equal conc. of solute compared to its environment

What are the four effects of Osmosis on animal vs. plant cells (two per cell)?

Animal:
1) Cell hypotonic = Crenation
2) Cell hypertonic = Lysis

Plant:
1) Cell hypotonic = Plasmolysis
2) Cell hypertonic = Turgor

What is Peptidoglycan?

Peptidoglycan - A tough, mesh-like material that makes up the cell wall of bacteria, which gives them shape and prevents lysis

What is the difference between Gram (+)/Gram (-) cell wall)?

Gram (+) - Bacteria has a thick peptidoglycan layer. Gram stain is purple.

Gram (-) - Bacteria has a thin peptidoglycan layer. Gram stain is pink

What are the 3 domains of life? List their differences.

1) Bacteria
-Prokaryotic
-Kingdom has the same name
-Has peptidoglycan

2) Archaea

-Prokaryotic
-Least diversity
-King has the same name

3) Eukarya
-Complex cells with membrane bound organelles

4 kingdoms:
a) Protista
b) Fungi
c) Plantae
d) Animalia

Who created cell theory and what are the 3 main ideas?

Mathias Schleiden and Theodor Shwann created cell theory.

1) All organisms are made of cells

2) Cells only arise from other cells

3) Cells are the smallest unit of life

Why do cells split at all, and not just keep growing?

Cells rely on diffusion, which requires good surface area: volume ratio and short travel distance for molecules. By splitting, they maintain high SA with low volume which is optimal for diffusion.

What are the two properties of microscopes?

1) Magnification - How much larger an object appears compared to its actual size = image size/actual size

2) Resolution - The ability to distinguish between two separate objects

Compare and contrast Animal cells vs. Plant cells.

Animal:
-no cell wall

-many small vacuoles
-has centrosomes
-no chloroplasts

Plant:
-has rigid cell wall

-has one large vacuole
-no centrosomes
-Has chloroplasts

What are the nucleus, nucleolus, and nuclear envelope?

Nucleus - a repository of genetic information

Nucleolus - rRNA synthesis site

Nuclear Envelope - surrounds the nucleus and controls movement of materials in and out

What are Ribosomes and their two sub-units?

Ribosomes - Protein synthesis machinery that are in all cells. Made of rRNA and ribosomal proteins.

Large Sub-Unit - Builds amino acid chains by catalyzing peptide bond formation
Small Sub-Unit - Reads mRNA and helps match mRNA codons with tRNA codons

What is the endomembrane system and it’s 5 main parts?

Endomembrane system - A system of membrane-bound organelles involved in cells internal transport or modification of materials

1) RER (makes proteins) and SER (makes lipids and stores Ca+2)

2) Golgi body - receives proteins from rER, then packages and transports them. Has a cis (receiving end) and trans (shipping) end.

3) Vesicles (including vacuoles and lysosomes) - storage and digestion of materials

4) Plasma Membrane - Controls movement of materials in and out of the cell

5) Nuclear Envelope - Controls movement of materials in and out of the nucleus

What are the 5 steps in preparing a specimen for a light microscope?

1) Kill specimen

2) Dehydrate (fix) it

3) Embed specimen in wax

4) Slice specimen with microtome

5) Stain specimen

What do lysosomes do and what role do they play in phagocytosis?

Lysosomes - Recycles old organelles and digests cells that have been engulfed

In phagocytosis:
1) Cell membrane engulfs it

2) Clathrin proteins pinch the cell membrane off to form phagosome

3) Lysosome’s membrane fuses with phagosome membrane (along with H+ pumps)

4) Phagosome pumps H+ in to lower PH and begin digestion

What are microbodies? Give an example.

Microbodies - A variety of enzyme-bearing vesicles

Example) Peroxisomes - Oxidates fatty acids which produces hydrogen peroxide (harmful), so catalase neutralizes it

What are mitochondria?

Cellular respiration site. Contains a folded inner-membrane and contains it’s own DNA

What are chloroplasts? What parts make up this structure?

Site of photosynthesis that is only present in plant cells and algae and it contains it’s own DNA

Made up of:
1) Chlorophyll
2) Stacks of thylakoids called grana

Compare how Light Microscopes and SEM magnify images and their resolution.

Light Microscopes: Condenses visible light through glass lenses, and the light passes through the specimen. Resolves up to 200nm

SEM: Condenses electrons with magnet coils to scan the surface of the specimen. Resolves up to 10nm

What are the two types of cells?

Prokaryotic:
-No membrane bound organelles
-Has capsule (a polysaccharide layer that prevents immune cell recognition)
-Often have cell walls
-Have pili and flagellum

Eukaryotic:
-Contains membrane-bound organelles
-Larger
-Plant cells contain cell walls
-Some have flagella

What are the two types of pili?

1) Fimbriae - used for attachment to surfaces

2) Sex Pili - helps in conjugation between bacteria (DNA swap)

What are the 4 ways to classify bacteria?

1) Gram stain

2) Flagella

3) Shape
a) coccus - round
b) bacillus - sausage
c) Vibrio - comma
d) spirillum - spiral

4) Aggregations
a) shape name = one
b) diplo = two
c) Stephalo = group
d) Stepto = strand

What are the 7 properties of life?

1) Cellular Organization (all life is made from cells)

2) Order (cells are highly organized and complex)

3) Sensitivity (cells sense/react to their environment)

4) Growth/reproduction using DNA

5) Energy utilization

6) Evolutionary adaptation

7) Maintains homeostasis

What are the 12 steps in the hierarchal organization of life?

Atoms, molecules, organelles, cells, tissues, organs, organ systems, population, species, community, ecosystem, biosphere

What are the two scientific approaches?

1) Reductionism - Breaking complex systems into parts to understand individual components

2) Systems thinking - Models how parts work together as whole to understand larger patterns escD

Describe the first 3 electron levels in terms of orbitals and # of electrons per orbital

1st layer - one orbital, 2e-
2nd layer - 4 orbitals, 4e-
3rd layer - 4 orbitals, 4e-

What are the 4 properties of water?

1) Highly polar

2) High specific heat capacity

3) Good solvent

4) Solid water is less dense than liquid water

Compare cohesion vs. adhesion

Cohesion - What water sticks to other water molecules by hydrogen bonding

Adhesion - When water sticks to other polar molecules or surfaces

Compare acids vs. bases

Acids - Donates H+ in water

Bases - Accepts H+ that are dissolved in water to form H2O

What are buffers? Give an example.

Buffers - Amphiprotic molecules that can either release or accept H+ ions in order to keep pH constant.

Example) Bicarbonate HCO3-

What are the main 7 functional groups?

1) Hydroxyl → OH

2) Carbonyl → C=O

3) Carboxyl → HO-C=O

4) Amino → NH2

5) Sulfhydryl → S-H

6) Phosphate → PO4

7) Methyl → CH3

What are isomers and the 2 main types?

Structural Isomers - Same empircal/molecular formulas, different structures

Stereoisomers
a) Enantiomers - Same formula and bonds, arranged differently in space (mirrored)

b) Diastereomers - Same formula and bonds, arranged differently in space (not mirrored)

Compare monomers vs. polymers and how they are formed/broken

Monomers - Simple chemical subunits like glucose - formed by hydrolysis (adding water)

Polymers - Built by linking monomers - formed by dehydration synthesis (removing water)

What are the two scientific research types?

Basic research
-expands knowledge

-driven by curiosity

-done in Academia

Applied research
-solves practical problems

-driven by specific needs

-leads to new technologies

-done in industry

What are emergent properties?

Characteristics that appear when parts of a system work together, but are not present in the parts themselves

Compare homologous vs. analogous structures

Homologous structures - Same structure, different use

Analogous structures - Same function, different evolutionary origins

Where are phospholipid bilayers found in cells?

1) Cell membrane

2) Membrane bound organelles

What are the 4 components of the cell membrane?

1) Phospholipid bilayer

2) Transmembrane proteins - Integral Proteins (protein channels/pumps)

3) Interior Protein Network - Cytoskeleton, spectrins, and clathrins

4) Glycoproteins (cell recognition) and glycolipids (helps in forming tissues)

Explain the 3 parts of the cytoskeleton

1) Microfilaments (movement and contraction)

2) Microtubules (transport and cell division)

3) Intermediate filaments (strength and stability)

What are the hydrophilic head, body, and hydrophobic tails of the phospholipid made of?

Head - Phosphate

Body - Glycerol

Tails - Fatty acid chain

What are the four types of molecules and what are they made of?

1) Carbohydrates - Molecules that have 1:2:1 ratio of carbon, hydrogen, and oxygen

2) Nucleic acids - chain of nucleotides (sugar, phosphate, and a nitrogenous base)

3) Proteins - long chains of amino acids

4) Lipids - long hydrocarbon chains that contain glycerol or fatty acid molecules

What are the 3 types of carbohydrates? Give three examples of each.

Monosaccharides - Single sugar - Glucose, fructose, and gelactose

Disaccharides - Two sugars - Lactose (Gluc + gelac), sucrose (gluc + fruct), maltose (gluc + gluc)

Polysaccharides - Many sugars - Starch (plant energy storage), glycogen (animal energy storage), cellulose (plant cell walls)

Compare purines to pyrimidines

Purines - 2 rings - Includes adenine and guanine

Pyrimidines - Single ring - Includes thymine, cytosine, and uracil

Which of the following are nucleotides?

ATP - Energy currency of the cell

DNA - Encodes information for amino aid sequences

RNA - A working copy of DNA’s instructions for amino acid sequences

What is the general amino acid sequence/structure?

Amino group, carboxyl group, variable group (R), and a hydrogen all attached to a carbon

What are the four levels of structure in proteins?

1) Primary - amino acid chain

2) Secondary - Pleated sheet

3) Tertiary - globular structure - formed when R groups interact

4) Quaternary - multiple tertiary structures binded together

Compare denaturation vs. dissociation of proteins?

Denaturation - when a protein loses it’s structure and function due to environmental conditions

Dissociation - loss of quaternary structure that can be reversed