DAT/Cells and transport

Which component of the phospholipid bilayer is hydrophilic?

Phosphate head is hydrophilic

Which component of the phospholipid bilayer is hydrophobic?

Fatty acid tails (hydrocarbon tail)

Which of the following most easily diffuses through the phospholipid bilayer?

Hydrophobic molecules

Which of the following cannot diffuse through the phospholipid bilayer?

Calcium. Steroids, CO2, Nitrogen, H2O, and Oxygen can diffuse

Polar molecules pass through the phospholipid membrane if they are __________.

Small and uncharged

hierarchy of membrane permeability

• (MOST) Small, Hydrophobic Molecules: O₂, CO₂, N₂, Steroid Hormones

• Small, Uncharged, Polar Molecules: H₂O, Urea, Glycerol, NH₃

• Large, Uncharged, Polar Molecules: Glucose, Sucrose

• (LEAST) Charged Ions: H⁺, Na⁺, HCO₃^-, K⁺, Ca²⁺, Cl^-, Mg²⁺

The glycocalyx is made up of __________.

Carbohydrates

The glycocalyx is present outside of some __________.

Animal cell membranes and bacterial cell walls

The functions of the glycocalyx include all of the following EXCEPT for one. Which one is the EXCEPTION?

❌Structural support of cell.

✅Cell adhesion, cell-to-cell recognition, maintenance of blood vessel walls, physical protection of cell from infection

Which of the following are common cell surface markers used regularly for cell-cell recognition?

Glycoproteins

The animal cell membrane is made up of __________.

Phospholipid membrane, cholesterol, membrane proteins

Which of the following is analagous to the role of cholesterol in plant cell membranes?

Sterols

Actin

protein that forms microfilaments, a major component of the cytoskeleton. Cell shape and movement, muscle contraction.

Glucocorticoids

• Type: Steroid (lipid-soluble) hormone

• Main example: Cortisol

• Made from: Cholesterol

• Produced in: adrenal cortex

• Transport: circulate bound to carrier proteins

• Receptor: intracellular (cytosolic/nuclear) → alters gene transcription

Major functions (high-yield)

Increase blood glucose (stimulate gluconeogenesis)

• Protein & fat breakdown

• Anti-inflammatory / immunosuppressive

• Stress response

Glycocalyx

Made of: Glycoproteins, Glycolipids. Carbohydrate chains projecting outside the cell

Main functions (DAT favorites)

• Cell–cell recognition

• Cell adhesion

• Protection of the cell surface

• Immune identification (self vs non-self)

Animal cells organelles (7)

• Nucleus (DNA storage)

• Mitochondria (ATP production)

• Rough & smooth ER

• Golgi apparatus

• Lysosomes (very common in animal cells)

• Centrioles

• Plasma membrane

(Unlike plant cells they don’t have: Cell wall, chloroplasts, large central vacuole)

Plant cell organelles

• Cell wall (cellulose) → protection & rigidity

• Chloroplasts → photosynthesis

• Large central vacuole → storage & turgor pressure

• Nucleus → DNA

• Mitochondria → ATP production

• Rough & smooth ER

• Golgi apparatus

• Plasma membrane

Bacteria

• Cell type: prokaryote

• DNA: circular DNA in a nucleoid region (no nucleus)

• Cell wall: peptidoglycan

• Ribosomes: 70S (smaller than eukaryotes)

• Organelles: ❌ none (no mitochondria, ER, Golgi)

• Size: smaller than eukaryotic cells

Archaea

• Cell type: prokaryote

• DNA: circular (nucleoid region)

• Cell wall: NO peptidoglycan

• Membrane lipids: ether-linked (not ester-linked like bacteria/eukaryotes)

• Ribosomes: 70S (like bacteria)

• Environment: often extreme (high heat, salt, acidity)

Fungi

• Cell type: eukaryote

• Nutrition: heterotrophic (absorption, not ingestion)

• Cell wall: chitin (not cellulose)

• Energy storage: glycogen

• Photosynthesis: ❌ none

• Reproduction: asexual and sexual (spores common)

Microtubules are made up of __________.

Tubulin

Microfilaments are made up of __________.

Actin

A transmembrane protein is __________.

Embedded from one side to the other side of the cellular membrane

A transmembrane protein is a type of __________.

Integral protein

Which of the following does the cell use to distinguish between self and foreign pathogens?

Glycoproteins

Glycoproteins are made of a protein molecule attached to a(n) __________.

Carbohydrate

Damage to recognition proteins on animal cells will cause which of the following?

Inability to distinguish self and foreign cells

Due to this membrane protein, the rate of water movement in the kidney can be increased.

Porin

Which of the following changes physical shape after binding to a specific molecule?

Carrier protein

Which of the following attaches cells to neighboring cells and provides stability with internal filaments and tubules?

Adhesion protein

Which of the following serves to bind to hormones and other chemical trigger molecules?

Receptor protein

Which of the following is found both in the kidneys and in plant root cells to facilitate the movement of water through cell membranes?

Porin

Channel proteins are most likely to be used to transport which of the following substances?

Polar molecules

Transport proteins use which of the following to transport material?

Active transport and facilitated diffusion

Active transport

• Requires ATP

• Uses membrane proteins (pumps or carriers)

• Moves solutes against the gradient (high→low)

• Maintains concentration differences

Facilitated diffusion

• No energy required

• Moves with gradient: high → low concentration

• Uses channel or carrier proteins

• Specific for the transported molecule

Simple diffusion

• No energy (ATP) required

• No proteins involved

• Moves high → low concentration

• Works best for small, nonpolar molecules

Which of the following may require ATP to function?

Carrier proteins

Osmosis

• No energy (ATP) required

• Water only

• Moves from low solute → high solute
  

  • (high water → low water)

• Across a semipermeable membrane

• Often through aquaporins (proteins)

Hypotonic

• Hypotonic solution → water enters cell → cell swells

Hypertonic

• Hyper tonic solution → water leaves cell → cell shrinks

Isotonic

• Isotonic solution → no net movement

Porins

channel proteins that form water-filled pores in membranes, allowing small polar molecules and ions to pass by facilitated diffusion.

• Porins → open channels, passive

Carriers

→ bind solute, change shape

Pumps

→ active transport, use ATP

A peripheral protein is attached by __________.

Loose attachment to the cellular membrane

An integral protein is __________

Embedded in the cellular membrane

Which of the following is used to store and protect the DNA in the eukaryotic cell?

Nucleus

Which of the following aids in organizing DNA into chromatin?

Histones

Histones

positively charged proteins that DNA wraps around to form nucleosomes, allowing DNA to be packaged tightly in the nucleus.

Histone types (know these)

• H2A, H2B, H3, H4 → core histones (8 total = histone octamer)

• H1 → linker histone (helps pack nucleosomes together)

Ribosomes

non-membranous complexes of rRNA and proteins that synthesize proteins by translating mRNA.

Sizes (DAT favorite)

• Prokaryotes (bacteria, archaea): 70S

• Eukaryotes (cytosol/ER): 80S

Nucleolus

• Function: makes ribosomes

• What happens there: rRNA transcription + ribosomal protein assembly

• Structure: not membrane-bound

• Location: inside the nucleus

• Absent during: mitosis (temporarily disappears)

When DNA is wrapped into a bundle with eight histone proteins, it is a __________.

Nucleosome

Which of the following is used to synthesize ribosomes in the eukaryotic cell?

rRNA

A toxin inhibits the nucleolus from functioning in the eukaryotic cell. Which processes will be directly affected by this?

Ribosome synthesis

The eukaryotic nucleus is contained within the __________.

Nuclear envelope

The movement of substances through the nuclear membrane is facilitated by __________

Nuclear pores

To transport mRNA and some proteins out of the nucleus, the nucleus has __________.

Nuclear Pores

Which of the following provides mechanical support to maintain the shape of the nucleus?

Nuclear lamina

Which of the following aids in chromatin organization?

Histones

All of the following can possess a cell wall EXCEPT one. Which one is the EXCEPTION?

Animal cell walls

Ribosomes are physically made up of __________.

rRNA and Protein

movement within the cytoplasm

Cyclosis

The organelle that assembles glycoproteins is called the __________

Rough ER

The organelle that produces lipids and steroid hormones is called the __________.

Smooth ER

A dysfunctional cell is unable to produce lipids. Which of the following organelles has been damaged?

Smooth ER

Which of the following is stored in the sarcoplasmic reticulum?

Calcium ions

organelles produces lysosomes?

Golgi apparatus

This organelle has digestive enzymes that break down molecules.

Lysosome

Which of the following organelles functions by packaging and transporting substances in vesicles?

Golgi apparatus

The flattened sacs in the Golgi apparatus are called __________

Cisternae

Which of the following organelles is common in liver and kidney cells?

Peroxisome

Which of the following is used by peroxisomes to oxidize substances?

Hydrogen peroxide

One of the most common proteins found in intermediate filaments is __________.

Keratin

Which of the following forms the spindle apparatus during cellular division?

Microtubules

The digestive enzymes inside lysosomes function at (a) __________.

Low pH

Intermediate filaments __________.

Provide support to maintain cellular structure

Microtubule Organization Centers are found everywhere besides __________.

Bacterial cells

Which of the following best describes the function of transport vacuoles?

Moves substances to different parts of the cell

Which of the following best describes the function of food vacuoles?

Holds nutrients to later break down food

Which of the following best describes the function of the central vacuole?

Expresses turgor to maintain cellular structure

Which of the following best describes the function of contractile vacuoles?

Pumps and collects water using active transport in some protist organisms

Microtubule Organizing Centers are found as __________.

9 x 3 array

Which of the following best describes the development of mitochondria in cells?

Endosymbiotic Theory

Which of the following best describes one of the functions of plastids?

Site of photosynthesis in plant cells

Which of the following best describes a function of the mitochondria?

Fatty acid catabolism

All of the following are found in both animal and plant cells EXCEPT for one. Which one is the EXCEPTION?

Plastid

If a mutation in animal cells causes mitochondria to be defective, then which of the following will occur?

Cells will die due to a lack of energy to drive basic functions

Which of the following best describes highly condensed chromatin in the eukaryotic cell?

Chromosome

Which of the following is not a membrane-bound organelle?

Ribosome

A lack of water can cause a plant to appear wilted due to a(n) __________.

Reduction in turgor pressure

A human disease results in an inability to synthesize enough steroid hormones. Which organelle is likely affected by the disease?

Smooth ER

Which of the following is the most common protein found in the extracellular matrix?

Collagen

Cells can bind to the extracellular matrix with ______

Hemidesmosomes

Which of the following best describes cyclosis (cytoplasmic streaming)?

The circular movement of the cytoplasm around cell transport molecules

Animal cells that experience mechanical stress like the skin tend to have ________

Desmosomes

Which cell junction produces a seal to prevent the movement of molecules between cells?

Tight junctions

Which of the following is the function of tight junctions?

Forms a seal preventing substances from traveling between cells

Animal cells that line the digestive tract in regions where substances need to go through the cells into the blood tend to have __________.

Tight junctions

Which animal cell junction provides tunnels that allow the movement of small molecules or ions?

Gap junctions