Unit 6: A Tour of the Cell

warm-up 3/5: How are plant and animal cells different? Same?

animal cells: lysosomes, centrioles, flagella

both: vacuoles, nucleus, ribosomes, mitochondria, ER, golgi, nucleolus

plant cells: large central vacuole, chloroplasts, cell walls, clorophil

2 types of cells:

1. Prokaryotes: Domain Bacteria and Archaea (Biggest distinguishing factor: No nucleus)

2. Eukaryotes (domain Eukarya): protists, fungi, plants, animals

A prokaryotic cell (bacteria)

Nucleus

• function: control center of cell that contains DNA

• surrounded by double membrane (nuclear envelope)

  • continuous with the rough ER

• Nuclear pores: control what enters/leaves nucleus

• chromatin: made of DNA + proteins; makes up chromosomes

• nucleolus: region where ribosomal subunits are formed

Warm up

A. Nucleolus- RNA synthesized here, produces ribosomes

B. Nuclear pore- areas where ribosomes are released

C. Nuclear envelope- double emmebrane that surrounds and protects nucleus

D. Chromatin- genetic material before it condenses into chromosomes

E. DNA- genetic material

F. RNA- protein synthesis

G. Chromosome- structures that carry genetic info

H. Genes- found on chromosomes, give us traits + characteristics,

Warm up 3/7: the functions of these parts

1. Nucleus- contains the genes, brian of the cells

2. ribosomes-protein synthesis

3. Golgi- packages, transports, sorting

4. smooth er- lipid synthesis, modifies lipids

5. rough er- protein synthesis/modification

6. vesicle- membrane sacs that contain nutrients, golgi apparatus

7. Chloroplast- site of photosynthesis

8. Mitochondrion- powerhouse of the cell where energy is made, cellular respiration

9. cytoplasm- what holds organelles in a cell, metabolic activities

10. plasma membrane- selective barrier that lets things in and out of cell

11. pili- help attach bacteria

12. cilia- tiny hairs that help remove foreign stuff

13. microvilli- cell receptors, hairlike, in digestive system, increase surface area so we can absorb nutrients

14. nucleolus- makes ribosomes, in nucleus

15. plasmid- horizontal gene transfer

16. central vacuole- plays a role in plant cell growth, contain water, waste, structure

17. lysosomes- used for digestion and remove waste, recycling units, found in immune system, white blood cells contain lots of

18. chromatin- makes up chromosomes

MRSA- Methicillin-resistant staphylococcus aureus

ribosomes

• function: (translation) protein synthesis and made of rRNA + proteins

• large subunit + small subunit

• types:

  • 1. free ribosomes: float in cytosol, produce proteins used within cells

  • 2. bound ribosomes: attached to ER, make proteins for export from cell

Endomembrane system:

• regulates lipid and protein modification, packaging, and transport

• performs metabolism functions (chemical reactions)

• Includes: endoplasmic reticulum, golgi apparatus, vesicles, lysosomes, cell membrane and nuclear envelope

Endoplasmic reticulum (ER) (Biosynthetic factory)

network of membrane and sacs

• types:

  • Rough ER: ribosomes on surface

  • function: transport and package proteins for secretion, send transport vesicles to Golgi, make membranes

  • Smooth ER: no ribosomes on surface

    • function: synthesize lipids, metabolize carbs, detox drugs and poisons and in muscles, they store Ca2+

Golgi Apparatus

• functions: synthesis and packaging of materials (small molecules) for transport (in vesicles); produce lysosomes and package lipids and proteins into vesicles

• series of flattened membrane sacs (vesicles)

  • cis face: receives vesicles

  • trans face: ships vesicles

Warm-up 3/10/25:

What are the functions of the endomembrane system? What organelles are included? 

Regulates lipid and protein modification, packages, and transports. 

1. endoplasmic reticulum  2. golgi apparatus 3. vesicles 4. Lysosomes 5. cell membrane  6. nuclear envelope

Lysosomes (only found in animal cells) 

• Originate in the Golgi Apparatus.

• Function: intracellular digestion of macromolecules and pathogens; recycle cell’s materials; performs programmed cell death when necessary (Apoptosis). 

• Contain hydrolytic enzymes (Break down).

• Prefer an acidic environment (low pH).

• Found a lot in white blood cells.

Vacuoles

• Function: storage of materials, (food, water, minerals, pigments, poisons) 

• Membrane-bound vesicles

• Ex. food vacuoles (formed by phagocytosis ), contractile vacuoles (regulates water pressure)

• Plants: Large central vacuole -- stores water, wastes and gives cells shape. 

Mitochondria (be able to draw and label)

• Function: site of cellular respiration.

• Double membrane: outer and inner membrane.

• Cristae: folds of inner membrane for increased surface area: contains enzymes for ATP production.

• Matrix: fluid-filled inner compartment. 

Continued--

• Mitochondrial DNA: Same as our Mamas

• Cellular Respiration= REDOX reactions transfer electrons from (glucose) by breaking the bonds which makes ATP, the energy controlling all biological processes. 

• Oxidation= electron loss Reduction= electron gain

• C6H12O6 + 6O2 →6CO2 + 6H2O + chemical energy 32_ -  36  (ATP)

Locations: 

1. Glycolysis- in cytoplasm 

2. Krebs Cycle - Matrix

3. Electron Transport Chain - Cristae

Warm up 3/11: Explain how proteins are manufactured in the cell and sent out and used in the body

and onto the rough ER. In the rough ER protein is synthesized and then through the golgi apparatus, they are sent out to the body for usage for structure, growth

1. start in the nucleolus which produces ribosomes that are sent out of the nuclear pores

2. rough er transports and modifies the amino acids and are sent to the

3. golgi apparatus where they are package, modified, and placed into vesicles

4. The vesicles are then sent to the plasma membrane and dispersed through exocytosis and used by the body

Chloroplasts

• double-membraned and site of photosynthesis

• thylakoid disks in stacks of grana-light dependent reactons; contain chlorophyll (pigments) for capturing light energy to form ATP and NADPH (enzyme)

• stroma (fluid)- Calvin cycle or dark reactions- carbon fixation is used to “fix” into organic molecules glucose (the food for the autotroph)

Endosymbiont theory (symbiogenesis)

• Mitochondria and chloroplasts share a similar origin

• Prokaryotic cells engulfed by ancestors of eukaryotic cells

• evidence:

  • double membrane structure

  • have their own ribosomes and DNA

  • reproduce independently within cell

  • want as many mitochondria as possible which means more cellular respiration, which means more energy

Peroxisomes (liver and kidney)

• functions: contain various enzymes that break down fatty acids (lipid biosynthesis); detox alcohol (catalase) as well as alcohol dehydrogenase; prevent kidney stones

• involves the production of hydrogen peroxide (H202)

Cytoskeleton: network of protein fibers

• Function: support/structure, mobility, regular biochemical activities

• 3 types: microtubules, microfilaments, intermediate filaments

Warm up 3/12:

carbohydrate- recenptors to identify cells and pathogens

phospholipids- hydrophilic heads hydrophobic tails

cholesterol- prevents tails from sticking together and keeps fluidity of membrane

integral protein- takes up the entire membrane and has channels that pass through substances

peripheral protein-

channel protein- area where substances more into and out of the cell

fluid mosaic model- because it must be flexible and fluid, It is called mosaic because of that intricate parts

Extracellular Matrix (ECM)

• outside plasma membrane

• composed of glycoproteins (ex. collagen and antibodies )

• function: strengthens tissues and transmits external signals to cell

Plant cells

• cell wall: protect plant, maintain shape

  • composed of cellulose and lignin

• plasmodesmata: channels between cells to allow passage of molecules and cellular communication (play a role in fighting off pathogens like fungal, bacteria, viral)

Surface area example (plant):

• root hairs: extensions of root epidermal cells; increase surface area for absorbing water and minerals. enables the transport water to the xylem vessels

• nutrients: phloem

Surface area example (animal):

small intestine: highly folded surface increases absorptions of nutrients

• villi: finger-like projections on small intestine wall that allow for nutrient absorption

• microvilli: smaller projections on each (found in large intestine too)

warm up 3/13: draw a chloroplast- label lamellae, stroma, grana, thylakoid, DNA, ribosomes, double-membrane. Where do light reactions occur? and Why? Where do dark reactions occur?

Light reactions occur in the thylakoid to capture light energy and turn it into chemical energy as the form of ATP and NADPH

Dark reactions occur in the stroma, and these occur by using the two energy molecules to make (chemical to chemical) CO2 into glucose. perform carbon fixation to make glucose

Chapter 7

Cell membrane (fluid mosaic model)

A. plasma membrane is selectively permeable

B. fluid mosaic model

• fluidity: membrane held together by weak interactions and keeps the flexibility

• mosaic: phospholipids, proteins, carbs, cholesterol

phospholipids

• bilayer

• amphipathic = *hydrophilic head* hydrophobic tail

• hydrophobic barrier: keeps unwanted materials out like wastes and pathogens

Membrane proteins

Carbohydrates

• function: cell-cell recognition or signaling; cell attachment; regulation of immune system

  • glycolipids and glycoproteins

• ex. blood transfusions, type-specific- A, B, AB, O

Passive Transport

• NO ENERGY ( ATP ) needed!

• Diffusion down concentration gradient (high →low concentration)

  • it is controlled by a) temperature b) pressure and c) concentration

  • small nonpolar molecules like hydrocarbons ( fuels ), CO2, O2, H2O

Facilitated Diffusion

• transport proteins (channel or carrier proteins) help hydrophilic substances cross

  • two ways:

    • provide hydrophilic channels

    • loosely bind/carry molecule across one at a time

  • ex. ions, polar molecules ( H2O, glucose)

Types of Facilitated DIffusion:

• glucose transport protein: (carrier protein) carries glucose into blood and levels are controlled by the hormone insulin released by the pancreas

• aquaporin: (channel protein) allows passage of H2O (ex: kidneys)

Active Transport

• Requires Energy (ATP)

• Proteins transport substances against the concentration gradient (low →high conc.)

• Ex: Na+ / K+ pump, proton pump, Endocytosis/Exocytosis 

1. Electrogenic Pump

: generate voltage across the membrane

2. Bulk Transport

: Transport of proteins, polysaccharides, and other large molecules.

Endocytosis- takes in macromolecules and particulate matter, and forms new vesicles from plasma membranes. Ex; carbs, lipids (cholesterol), proteins, pathogens by white blood cells

Exocytosis; vesicles fuse with the plasma membrane, and secrete contents out of the cell (proteins and lipids). Ex: Pancreas- insulin & Brain- neurotransmitters

Types of Endocytosis

• Phagocytosis:

“Cellular eating” - solids 

Ex: WBC devouring pathogens 

• Pinocytosis:

“Cellular drinking” - fluids

Ex: microvilli in SI absorbing nutrients 

• Receptor-Mediated Endocytosis (RME) : 

Ex: Specific receptors on cell surface indicate what to engulf, cells can absorb hormones, cholesterol, pathogens and nutrients

Warm-up March 08 2025

Draw A mitochondria. Label cristae, matrix, glycolysis, electron transport chain, krebs cycle, dna, ribosomes, double membrane. 

Write out chemical equations for cellular respiration.

C6H12O6 + 6O2 → 6CO2 + 6H2O + Energy (ATP)

Osmoregulation (passive)

• Control salt & water balance in the body

  • Contractile Vacuole: in protists, it is a “bilge pump” that forces out H2O as it enters by osmosis.

• Ex. Paramecium (protist)-contractile vacuole, fresh and saltwater fish - gills, humans-  kidney

External environments can be hypotonic, isotonic, or hypertonic to internal environments of cell

Warm up 3/19: what happens to RBC’s (red blood cells) and plant cells in the following solutions → hypotonic (C6H12O6) hypertonic (salt water) isotonic

erythrocytes (red blood cells)→ Hemolysis (cells expand then burst) Plasmolysis (cell shrivels) Equilibrium

plant cells → Turgid, Plasmolysis, Flaccid

Video notes

Osmoregulation

• fish in the ocean are hypotonic compared to the water in its environment

cytolysis- bursting of cells

why is it that we can not drink ocean water? bc our body is trying to get rid of salt being injected and this happens with our kidneys, this releases water in our body and we become dehydrated