CHAPTER 6 A Tour of the Cell

You Must Know 3 diff. prokaryotic and eukaryotic cells. Common organelles (Plant/Animal) Unique organelles (Plant/Animal) Organelles > Cell Function Size and Shape affect rate of nutrient/waste

Tuesday December 1st Agenda: Checklist for Chapter 6 Due Thursday Videos: 1.Introduction to CellsIntroduction to Cells

Wednesday December 2, 2015 Agenda: 1. Surface area to volume demonstration 2. Checklist for Chapter 6 Due Tmrw Videos: 1.Cell SizeCell Size

Size range of cells Note that light microscopes can not magnify as well as electron microscopes Scale of the Universe:

What factors constrain cell size?

Surface Area to Volume Ratios Need a large surface area to accommodate for growing demands of cell – energy, nutrients, wastes, gasses More cells vs. Larger cells

surface area to volume ratio Cells must be small to maintain a large surface area to volume ratio Large S.A. allows  rates of chemical exchange between cell and environment

Practice Problem Simple cuboidal epithethial cells line the ducts of certain human exocrine glands. Various materials are transported into and out of the cell by diffusion. What would be the volume of the larger cell in um 3 ? SA Formula: 6 x S 2 Volume: S 3 S = length of side 10 um 20 um

Animal Surface Area Example (Animal): Small Intestine: highly folded surface to increase absorption of nutrients – Villi – Villi: finger-like projections on SI wall – Microvilli – Microvilli: projections on each cell

Diverticulitis of the colon

Plant Surface Area Example (Plant): Root hairs Root hairs: extensions of root epidermal cells; increase surface area for absorbing water and minerals

Thursday – December 3 rd Agenda: Ch 6 Check for Understanding Microscope Lab

Chapter 6 Check for Understanding 1.What are the 2 main types of cells? Which Domains do they consist of? 2.List 3 ways that eukaryotes differ from prokaryotes.

Special Note: Archaea and bacteria generally lack internal membranes and organelles and have a cell wall.

2 Types of Cells: 1.Prokaryotes: Domain Bacteria & Archaea 2.Eukaryotes (Domain Eukarya): Protists, Fungi, Plants, Animals

A Prokaryotic Cell (bacteria)

Commonalities Prokaryote and Eukaryote Plasma Membrane Ribosomes (Not membrane bound in P) DNA: – Prokaryote: Region, Circular Chromosome – Eukaryote: Nucleus, Linear Chromosome

Summary Prokaryote Vs. Eukaryote “before” “kernel” No nucleus, DNA in a nucleoid Cytosol No organelles other than ribosomes Small size Primitive i.e. Bacteria & Archaea 1-10 um “true” “kernel” Has nucleus and nuclear envelope Cytosol Membrane-bound organelles with specialized structure/function Much larger in size More complex i.e. plant/animal cell um

Chapter 6 Check for Understanding Animal CellPlant Cell Compare and contrast Animal vs. Plant Cells

Parts of plant & animal cell p

Endosymbiont theory Mitochondria & chloroplasts share similar origin These prokaryotic cells engulfed by ancestral eukaryotic cells Evidence: – Double-membrane structure – Have own ribosomes & DNA – Reproduce independently within cell

For the AP Exam Know the function of the cytoskeleton. Not needed. Specifics on structure & function of: 1.Microtubules 2.Microfilaments 3.Intermediate filaments

Centrioles: made of microtubules – Aid in cell division, move to the poles to help the cell divide

For the AP Exam NOT NEEDED FOR THE EXAM…. 1.Plasmodesmata 2.Gap junctions 3.Tight junctions 4.Desmosomes

Friday December 4 th Agenda: Organelles Review Chapter 7 Checklist – Due Monday Warmup Worksheet Chapter 6 Part 1

Organelles What is the function of an organelle? Why does the cell compartmentalize?

What are some commonalities between the nucleus, mitochondria and chloroplast? StructureFunction

Mitochondria Function: site of cellular respiration Double membrane: outer and inner membrane Cristae: folds of inner membrane; contains enzymes for ATP production; increased surface area to  ATP made Matrix: fluid-filled inner compartment

Chloroplasts Function: site of photosynthesis Double membrane Thylakoid disks in stacks (grana); stroma (fluid) Contains chlorophylls (pigments) for capturing sunlight energy

Other types of plastids Amyloplastids: colorless plastids that store starch in roots and tubers Chromoplasts: Store colored pigments for fruits and flowers Tubers are various types of modified plant structures that are enlarged to store nutrients. Used to survive the winter or dry months, to provide energy and nutrients, and a means of asexual reproduction.

What is the relationship between the nucleus and the endomembrane system?

Nucleus Function: control center of cell Contains DNA (code for making proteins) Surrounded by double membrane (nuclear envelope) – Continuous with the rough ER – Supported by protein filament network called nuclear lamina Nuclear pores: control what enters/leaves nucleus Inside of the nucleus – Nuclear matrix – internal support, protein framework Chromatin: complex of DNA + proteins; makes up chromosomes Nucleolus: region where ribosomal subunits are formed Prokaryote: Nucleoid Region- dense region

Nucleus Contains DNA Function: control center of cell Surrounded by double membrane (nuclear envelope) – Continuous with the rough ER Nuclear pores: control what enters/leaves nucleus Chromatin: complex of DNA + proteins; makes up chromosomes Nucleolus: region where ribosomal subunits are formed

DNA to Chromatin to Chromosome

Do all eukaryotic cells have a single nucleus?

Ribosomes Function: protein synthesis Composed of rRNA + protein Large subunit + small subunit Types: 1.Free ribosomes: float in cytosol, produce proteins used within cell 2.Bound ribosomes: attached to ER, make proteins for export from cell

ENDOMEMBRANE SYSTEM: Regulates protein traffic & performs metabolic functions in the cell Nuclear Envelope ER Golgi Lysosomes Vesicles Vacuoles Plasma Membrane

Endoplasmic Reticulum (ER) “Within the cytoplasm” - “Little net” 1.Rough ER: ribosomes on surface Function: package proteins for secretion, send transport vesicles to Golgi, make replacement membrane 2.Smooth ER: no ribosomes on surface Function: synthesize lipids, metabolize carbs, detox drugs & poisons, store Ca 2+

What types of lipids are synthesized in the smooth ER? Where (in the human body) would we find a lot of SER for this purpose?

What type of body cells would have a high number of Smooth ER for detoxification?

Barbiturates – CNS Depressants Anxiety, Seizures and Sleep Disorders Example: Alcohol Induce the proliferation (growth of production) of smooth ER and it’s detoxification enzymes (increase the rate) In turn, this increases your tolerance Can also decrease effectiveness to drugs you need – like antibiotics

Golgi Apparatus Function: synthesis & packaging of materials (small molecules) for transport (in vesicles); produce lysosomes Series of flattened membrane sacs (cisternae) Cis face: receives vesicles Trans face: ships vesicles

Lysosomes Function: intracellular digestion; recycle cell’s materials; digestion in prokaryotes Contains hydrolytic enzymes

What happens if a lysosome accidentally ruptures in the cell? What is the name of the lysosomal disorder where individuals lack the enzyme needed to breakdown lipids?

Peroxisomes Functions: break down fatty acids for the mitochondria; detox alcohol Contain catalase, Involves production of hydrogen peroxide (H 2 O 2 )

Vacuoles Function: storage of materials (food, water, minerals, pigments, poisons) Eg. food vacuoles, contractile vacuoles (pump) Plants: large central vacuole -- stores water, ions

Why would the construction of a protein take place through a long system? Why not just one organelle?

Cilia & Flagella Flagella: long and few; microns, propel through water Cilia: short and numerous; 2-20 microns, locomotion or move fluids

Let’s begin Chapter 7!