Sydney Roth, Lina Rivetti, Annabel Kopell

The most vital asset in regulating what enters and leaves the cell is the cell membrane. Both prokaryotic and eukaryotic cells contain a cell membrane and the membrane functions in the same way for all. Necessary Functions:o Separates internal metabolic reactions from

external surroundingso Helps excrete the cell’s wasteo Responsible for the intake of substances needed for

cell functions o Protective barrier against water from its

environment

Topic 1

• The cell membrane is composed of a phospholipid bilayer and proteins.

• The phospholipids in the bilayer have hydrophilic heads and hydrophobic tails allowing the membrane to regulate water entry.

• The proteins embedded in the bilayer are either transport proteins, receptor proteins for odor, taste, and hormones, or channels to control the entry/exit of ions and other substances that cannot travel through the bilayer.

Cell membranes help organisms maintain homeostasis by controlling what substances enter/leave the cell. Passive Transport- a process by which substances can cross the cell membrane without any input of energy by the cell.• Facilitated diffusion- a process used for molecules

that cannot readily go through the cell membrane. They are molecules that are not soluble in lipids or are too large to pass through the membrane. Use carrier proteins.

Active Transport- a process by which cells must use energy to transport substances in/out of the cell

• Endocytosis- the process by which cells ingest external fluid, macromolecules, and large particles, including other cells

• Exocytosis- the process by which a substance is released from the cell through a vesicle that transport the substance to the cell surface and then fuses with the membrane to let the substance out of the cell

• The golgi body is responsible for packaging the cell secretions in secretory vesicles for transport out of the cell through the membrane.

http://www2.estrellamountain.edu/faculty/farabee/biobk/endocytosis.gif

http://www.pbslearningmedia.org/asset/tdc02_int_membraneweb/

http://www.cytochemistry.net/cell-biology/Gol8.jpg

Introduction

The cytoskeleton is a network of thin tubes and filaments that crisscrosses the cytosol• Maintains cell shape• Anchors organelles and enzymes to specific regions of the

cell• Contractility and movement (amoeboid movement)• Intra cellular transport tracks for vesicle and organelle

movement by motor proteins

In order for a cell to function properly, it must have a particular structure. The cell also must be mobile if necessary and be able to move materials over the surface of stationary cell. The cytoskeleton forms the structure of the cell.

PowerPoint made by Andrew Zheng, Emmaline Stoddard, and Meghan Sardis

Parts of Eukaryotic Cytoskeleton• Microfilaments- long

threads of actin– Contribute to cell movement

• Microtubules- hollow tubes of tubulin– Maintain cell shape, anchor

organelles, contribute to cell movement, track for motor proteins

• Intermediate Filaments- rope-like fibrous proteins– Provide structural

reinforcement, anchor organelles, keep nucleus in place

Parts of Prokaryotic CytoskeletonThe cytoskeleton structures in prokaryotes and eukaryotes are different, though the functions of these structures are similar• FtsZ– Forms filaments

• Mreb and ParM– Maintenance of cell shape

• Crescentin– Maintaining cell shape

Cellular Movement• Cilia- short, hair-like

appendages extending from the surface of a living cell– “row” the protists like

thousands of oars– Short– Found in eukaryotic cells

• Flagella- long threadlike appendages on the surface of a living cell– Whip back and forth in a

jerky fashion to propel cell– Longer than cilia– Found typically in

prokaryotic cells, sometimes in eukaryotic cells

Citations and Links• www.diffen.com• http://

www.stolaf.edu/people/giannini/flashanimat/cellstructures/Motor%20protein.swf

• http://www.stolaf.edu/people/giannini/flashanimat/cellstructures/micro%20slide.swf

• http://www.stolaf.edu/people/giannini/flashanimat/cellstructures/microtubuletransport.swf

• http://learn.genetics.uutah.edu/content/begin/cells/

The Purpose of Nutrients in a CellObtaining and metabolizing nutrients is necessary in order for a cell to complete several life processes. Cells acquire nutrients and convert it to energy to move, divide, produce secretory vesicles, contract, and reproduce. Without energy, a cell wouldn’t be able to “fuel” its internal organelles and perform any of the essential functions of life.

Cell ComparisonsProkaryotes/Eukaryotes- Eukaryotes contain internal organelles that are not present in prokaryotes, such as the mitochondria, that assist in obtaining and metabolizing nutrients.

Animal Cells/Plant Cells- Plants cells contain chloroplasts that are not present in animal cells.- Both contain the mitochondria that are essential in producing ATP the cell’s primary energy source.- Plant cells: Photosynthesis- Animal cells: Diffusion

Emily Carrieri, Stella Hung & Sandro Conte

Structures Involved• Cell Membrane- Allows specific nutrients to enter the cell from outside surroundings - Protects internal metabolism from harmful conditions outside the cell

• Mitochondria- Takes food (in form of sugar) and combines with oxygen to produce ATP. - ATP is the primary energy source for the cell.

Structures Involved (cont.)Chloroplast (plant cells only)- The chloroplasts contain a green pigment Chlorophyll, which absorbs energy from sunlight. - The energy converts water and carbon dioxide into sugars (like glucose) that the mitochondria can convert into ATP.

Prokaryotes- Prokaryotes obtain and metabolize nutrients differently due to the fact that they lack the internal organelles that eukaryotes have. - Prokaryotes obtain their nutrients through the process of diffusion.

- Storage Granules: After the nutrients are metabolized through a series of chemical reactions in the cytoplasm, they are stored in storage granules in some form of energy (glycogen, lipids, etc.) and are used as needed.

Cells must Grow, Develop, and Reproduce Overview

• By Jackie Romankow, Emma Williams, Brian Zeng, and Vineet Parikh.

• This is the cell cycle- the repeating of set events in the life of a cell• First interphase happens• Then cell division• Why?– This cycle happens to replace dead

or dying cells, and/or to produce a new organism.

http://www.cellsalive.com/cell_cycle.htm

Centrosomes and Cytoplasm

• http://cellsalive.com/mitosis.htm• A centrosome only functions during mitosis

• Cytokinesis is the division of cytoplasm of cells

Nucleus

• This is arguably the most important organelle involved in cell reproduction and growth.

• Mitosis is the cycle in which the Nucleus divides

Differences in the CyclePlant vs. Animal Eukaryotes vs. Prokaryotes

Proteins Synthesis

• The process by which cells synthesize, modify, and ship proteins to their respective destinations.

• Group Members: Nicki Wang, Ethan Goldring, Amelia Fruda, and Gavin Van Skiver. http://

www.proteinsynthesis.org/wp-content/uploads/2013/02/protein-synthesis-ribosome.jpg

Process of Protein Synthesis1. Proteins are assembled in

the ribosomes by RNA, which act on instructions from the DNA.

2. Vesicles transport proteins to the Golgi Apparatus.

3. The Golgi Apparatus modifies proteins and ‘re-labels’ them into new vesicles.

4. Vesicles release proteins that have destinations outside the cell.

http://4.bp.blogspot.com/-k0yymaOn57o/T59yTtItXYI/AAAAAAAAERY/Xc_dZTuFYrQ/s1600/MJ+2012+howproteinsynthesisworks.jpg

The process is broken into 2 steps: Transcription, then Translation.

Organelles Involved• Nucleus: where the process

begins (with DNA and RNA)• Rough Endoplasmic Reticulum:

place where Ribosomes are attached in cytoplasm.

• Ribosomes: where the proteins are synthesized.

• Golgi Apparatus: where the proteins are modified and packaged into different vesicles, so they can be moved to different regions of the cell.

• Vesicles: the organelles that release the proteins.

http://www.enchantedlearning.com/subjects/animals/cell/anatomy.GIF

Why it is Important?• Protein synthesis allows new proteins to be

created, replacing dying or diseased proteins.– Proteins are important to cell function!

• Protein synthesis also allows DNA to have a hand in the daily function of a cell.

A Helpful Animation:http://www.stolaf.edu/people/giannini/flashanimat/cellstructures/endomembrane%20protein%20synthesis.swf

Any Differences?

• In a eukaryotic cell the process of transcription occurs in the nucleus, while translation occurs in the cytoplasm. In prokaryotic cells, both stages occur in the cytoplasm

• When protein synthesis occurs in a ribosome not located inside the Rough ER, the proteins produced never leave the cell.

http://www.odec.ca/projects/2004/mcgo4s0/public_html/t3/antisense1.gif

Storing and Digesting Nutrients in CellsHaley Frey, Jonathan Rich, Sarah Rosa

Why is storing and digesting nutrients so important for cell function?• Cells need nutrients for energy (ATP), cellular

functions, and to create new tissues and cells.• A cell can’t use food until it has been digested. • Cells also need to neutralize dangerous

substances.

Lysosomes• vesicles that bud from the Golgi apparatus• contain hydrolytic enzymes to break down

substances into useful material– carbs, lipids, proteins, nucleic acids

• Autophagy: they digest worn out organelles• Autolysis: lysosomes in a cell breaking down

that cellhttp://highered.mcgraw-hill.com/sites/9834092339/student_view0/chapter4/lysosomes.html

Peroxisomes

• found in the kidney and liver cells• deal with harmful substances – free radicals (oxygen ions) which are harmful

• detoxify alcohol and other drugs• digests hydrogen peroxide (H2O2) • break down fatty acids for energy

Digestion ProcessPLANT CELLS

Organelles involved: - Large vacuole: stores digested

material, act as lysosomes for the plants

- Peroxisomes: convert fatty acids to sugar and assist chloroplasts

What happens: material enters the cell and the peroxisomes begin to digest them. The digested material is then stored in the vacuole.Decaying organelles are broken down and reused in other places.

ANIMAL CELLSOrganelles involved:- Lysosomes: contain enzymes to

digest bacteria and other substances- Peroxisomes: digest harmful H2O2

What happens: material enters the cell and the lysosomes and peroxisomes begin to digest it. The useful material is transferred to the mitochondria to be used for energy.

Decaying organelles are broken down and reused in other placed.