Unit 2: Cells Mr. Nagel

Meade High School

Warm Up

• Construct diagrams of: – E. Coli – Animal Cell (Liver) – Plant Cell

– Indicate which are present in each:

• Cell wall, plasma membrane, cytoplasm, pili, flagella, ribosomes, nucleoid, rough ER, golgi apparatus, mitochondrion, nucleus.

IB Syllabus Statements • 2.3.4

– Compare prokaryotic and eukaryotic cells. • 2.2.4

– State that prokaryotic cells divide by binary fission. • 2.2.1

– Draw and label a diagram of the ultrastructure of Escherichia coli (E. coli) as an example of a prokaryote.

• 2.2.2 – Annotate the diagram from 2.2.1 with the functions of each named structure.

• 2.2.3 – Identify structures from 2.2.1 in electron micrographs of E. coli.

• 2.3.1 – Draw and label a diagram of the ultrastructure of a liver cell as an example of an animal cell.

• 2.3.2 – Annotate the diagram from 2.3.1 with the functions of each named structure.

• 2.3.3 – Identify structures from 2.3.1 in electron micrographs of liver cells.

• 2.3.5 – State three differences between plant and animal cells.

• 2.1.7 – State that multicellular organisms show emergent properties.

• http://click4biology.info/c4b/2/cell2.htm

Prokaryotes v. Eukaryotes • HW: Compare and Contrast with a partner

– Common structures – How do they reproduce?

• Binary Fission v. Mitosis

Prokaryotic Cell (E. Coli)

Individual Cells are Either:

• “Round” – i.e.: staphylococcus

• “Spirial”

– i.e. Spirillum

• “Rod Shaped” – i.e. Anthrax

Prokaryotes in Pictorial Form

Up Close and Personal… Cell Membrane -Controls passage of materials in and out of cell -Can be infolded (called a mesosome) Cytoplasm -Fluid space where metabolism takes place Ribosome -Freely floating site of protein synthesis NO membrane bound organelles!

Some Prokaryotes have a cell wall…

• Gives shape, support and protection to the plasma membrane and cytoplasm of the cell.

• Made of peptidoglycan* (protein-sugar molecules).

*different than plant cell walls, which

are made of cellulose

Flagellum and Pili • Some bacteria have one or more Flagellum. (motility)

• Pili are short fibers found on some bacteria. (cling)

Capsules • A special mucus-like protective coating

found on some disease-producing bacteria.

Gram+ and Gram-

• Gram-positive bacteria: – Stain purple – Have a very thick cell wall

(because of lots of peptidoglycan).

• Gram –negative bacteria: – Stain pink – Cell walls only contain a

few layers of peptidoglycan – Many are pathogenic,

meaning they can cause disease in a host organism.

Eukaryotes (Plants and Animals)

• Discuss with someone next to you differences between plant and animal cells. (Minimum 3)

Eukarytoic Cell (Animal)

Liver Cell

Ultrastructure of a liver cell. 1:Nucleolus; 2:Chromatin; 3:Dense Chromatin; 4:Nuclear Pores; 5:Mitochondria; 6:Rough ER; 7:Ribosomes; 8:Golgi Apparatus; 9:Smooth ER;10:Peroxisomes; 11:Lysosomes; 12:Bile Capillary; 13:Desmosomes; 14:Microvilli.

-Nucleolus: Ribosome synthesis -Golgi: Cis Trans

Eukaryotic Cell (Plant)

Onion Cell

Emergent Properties

• Quite simply, “The whole is greater than the sum of its parts.” – Imagine a mouse trap.

• In studying the spring, woodblock, and cheese, you don’t necessarily SEE a design for a mousetrap.

• Placing the items together allows for a whole new level of use for these parts.

– Applies to multicellular organisms.

Research

• Individually or in pairs, select an organelle. – Construct a 6-8 sentence paragraph about:

• Structure • Function • Eukaryotic (plant, animal) or Prokaryotic or both • Catalogue any subgroups that may be a part

– Ex: Plastids Chloroplast, chromoplast, amyloplast

• What would happen to a cell without it?

Warm Up

• State the cell theory (three parts).

• Which increases faster as a cell expands: Surface Area or Volume? – What does this mean in terms of the

survivability of larger cells?

• Which type of microscope would be best for observing the internal structure of a bacteria?

Webquest

• Cells and Organelles

IB Syllabus Statements • 2.3.6

– Outline two roles of extracellular components. • 2.4.1

– Draw and label a diagram to show the structure of membranes. • 2.4.2

– Explain how the hydrophobic and hydrophilic properties of phospholipids help to maintain the structure of cell membranes. • 2.4.3

– List the functions of membrane proteins. • 2.4.4

– Define diffusion and osmosis. • 2.4.5

– Explain passive transport across membranes by simple diffusion and facilitated diffusion. • 2.4.6

– Explain the role of protein pumps and ATP in active transport across membranes. • 2.4.7

– Explain how vesicles are used to transport materials within a cell between the rough endoplasmic reticulum, Golgi apparatus and plasma membrane.

• 2.4.8 – Describe how the fluidity of the membrane allows it to change shape, break and re-form during endocytosis and exocytosis.

• 2.5.1 – Outline the stages in the cell cycle, including interphase (G1, S, G2), mitosis and cytokinesis.

• 2.5.2 – State that tumours (cancers) are the result of uncontrolled cell division and that these can occur in any organ or tissue.

• 2.5.3 – State that interphase is an active period in the life of a cell when many metabolic reactions occur, including protein synthesis, DNA replication

and an increase in the number of mitochondria and/or chloroplasts. • 2.5.4

– Describe the events that occur in the four phases of mitosis (prophase, metaphase, anaphase and telophase). • 2.5.5

– Explain how mitosis produces two genetically identical nuclei. • 2.5.6

– State that growth, embryonic development, tissue repair and asexual reproduction involve mitosis. • 2.1.8

– Explain that cells in multicellular organisms differentiate to carry out specialized functions by expressing some of their genes but not others. • 2.1.9

– State that stem cells retain the capacity to divide and have the ability to differentiate along different pathways. • 2.1.10

– Outline one therapeutic use of stem cells.

• http://click4biology.info/c4b/2/cell2.htm

Lipid Bilayer • What is the Extracellular Matrix?

– Support, Adhesion, and Movement – Hydrophilic vs. Hydrophobic

• Fluidic vs. Viscous (unsaturated vs. saturated HC tails) • Lateral movement common; layer flip-flop rare • http://www.johnkyrk.com/cellmembrane.html

– Membrane Proteins (Support/Transport)

Diffusion and Osmosis

• Diffusion – Molecules moving from higher

to lower concentration – Osmosis is the diffusion of

water molecules

• Turgor Pressure – Water pushing against cell

membrane from inside

Passive and Active Transport

• Passive (no Energy) – Simple Diffusion – Facilitated Diffusion

• Protein structure helps molecule travel across

– Gated Channels • Separate stimulus

opens/closes ‘tunnel’

• Active (ATP) • Electrogenic pump (H+) • Sucrose-H+ cotransport • Na (out) / K (in) pump

•Exocytosis •Secretion of proteins

•Endocytosis •Internalization of materials

•Phagocytosis (food) •Pinocytosis (fluids) •Receptor-Mediated endocytosis

Transport: Vesicles

Consider…

• How does your skin know to grow cells when you get cut, but does not grow when you are undamaged?

• Do your cells split on a regular basis? How often? What would be the purpose?

• Could you define the ‘events’ in the life of a cell?

Cell Cycle • Interphase

– G1, S, and G2 • G = Gap • S = Synthesis

– Mass production! • Cancer cells

– What do you think goes wrong?

• CDKs (cyclin dependent kinases) ex: p57

• Perfect reproduction (two identical nuclei)

• Growth, embryonic development, tissue repair, asexual reproduction

• P.M.A.T.

Mitosis

Name That Phase…

Cell Cycle Project

• How long does a typical cell spend in each phase of Mitosis/Cell Cycle?

• Let’s consider an onion root tip cell… – http://www.biology.arizona.edu/cell_bio/activiti

es/cell_cycle/cell_cycle.html

Warm Up

• What macromolecules are part of the extracellular matrix?

• What two molecules can pass through the lipid bilayer unhindered?

• Plant cells prefer ___tonic conditions, whereas animal cells prefer ___tonic conditions.

• The phase of the cell cycle in which DNA is replicated is ___phase.

Cell Cycle Project

• How long does a typical cell spend in each phase of Mitosis/Cell Cycle?

• Let’s consider an onion root tip cell… – The average cycle duration is 24 hours.

Interphase Prophase Metaphase Anaphase Telophase TOTAL

Quantity 36

Percent 100%

Time 24 hrs

Interesting Thoughts…

• In the human body, the rate of mitosis is believed to be 25 million cells produced every second!

• That comes out to 2 trillion cells per day!

• Cells that divide rapidly – Skin, Epithelial,

Bone Marrow • Cells that must be

stimulated to divide – Liver

• Cells that do not divide – Nerve, Muscle

Circle Map – Stem Cells

• Cells in multicellular organisms differentiate to carry out specialized functions by expressing some of their genes but not others.

• Stem cells retain the capacity to divide and have the ability to differentiate along different pathways. There are a variety of levels.

• There are numerous therapeutic applications of stem cells – both currently in use and theorized.

Stem Cells and Specialization

Warm-up

• Outline the stages in the cell cycle.

• Outline the events of the four phases of Mitosis.

• What life processes are evidenced by Mitosis?

Warm-up

• State three differences between plant and animal cells.

• Define Diffusion and Osmosis.

• How can/could stem cells be used therapeutically?