7th Grade Lesson - Brooke Jones

Unit 7

The Protector of the cell

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By: Brooke E. Jones

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The Cytosis Twins

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Introduction

Are we ready to learn about all that is the Plasma Membrane and its Function?

There are 5 key components we will discuss:1. Fluid Mosaic 2. Selectively Permeable 3.Passice Transport 4. Active Transport 5. Exocytosis and Endocytosis

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Fluid Mosaics

The fluid mosaic model is stucture of the plasma membrane. The mosaic: Represents the "organization" of the proteins in the lipid bilayer. The Fluid: Represents the fluidity of the phospholipids of the bilayer.

Phospholipids

Phospholipds are amphipathic= containing both hydrophobibc (tails) and hydrophilic (heads) regions.Hydrophobic: Do not like water; "water-fearing". Hydrophilic: Likes water; "water-loving".

The membrane contains multiple components: - Carbohydrates - Cholesterol (animal cells) - Peripheral Protiens - Integral Proteins - Gylcolipids - Glycoproteins - Fibers of Extracellular matrix (ECM)

Click the picture for video explanation.

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Fluid Mosaics

The fluid mosaic model is stucture of the plasma membrane. The mosaic: Represents the "organization" of the proteins in the lipid bilayer. The Fluid: Represents the fluidity of the phospholipids of the bilayer.

Phospholipids

Phospholipds are amphipathic= containing both hydrophobibc (tails) and hydrophilic (heads) regions.Hydrophobic: Do not like water; "water-fearing". Hydrophilic: Likes water; "water-loving".

The membrane contains multiple components: - Carbohydrates - Cholesterol (animal cells) - Peripheral Protiens - Integral Proteins - Gylcolipids - Glycoproteins - Fibers of Extracellular matrix (ECM)

Click the picture for video explanation.

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More information

The phospholipd tails can either be saturated or unsatured.Cholesterol works as stiffness control - when the temperatures get low it prevents the bilayer from getting stiff but at regular temperatures keeps the phospholipids from becoming too fluid.

Integral Proteins: This protein goes through the hydrophobic region of the phospholipid bilayer. Peripheral Proteins: They are bound to the surface of the membrane or an integral protein and do NOT go through the bilayer.

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Protein Functions

1.Transport: Provides transport across the membrane. 2.Enzymatic Activity: This is built into the membrane and is important for metabolic pathways. 3.Signal Transduction: Signaling molecule to receptor. 4.Cell-Cell Recognition: Name tags for cells. 5.Intercellular Junctions: The connecting of two cells by two cellular proteins.

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Selective Permeability

Definition: The property of biological membranes that allows them to regulate the passage of substances across them.

Small hydrophobic, nonpolar molecules have an easy time passing through the membrane. Examples: CO2, O2

Video

Continuing the Topic

Transport Proteins

Definition: A transmembrane protein that helps a certain substance or class of closely related substances to cross the membrane.

There are 2 categories: Channel or Carrier Proteins 1. Allows for a molecule to pass through the membrane, acting as a tunnel for those molecules that can not pass through as easily Example: Aquaporins= Facilitates osmosis 2. Holds on to the molecule and transports them through the membrane, like a taxi.

Passive Transport

Does not require energy!

Goes from high to low concentration (down the concentration gradient).

• Diffusion - The random thermal motion of particles of solids, liquids or gases
• Facilitated Diffusion - The movement of molecules with a little help, still not requiring extra energy
• Osmosis - The diffusion of water

Video!

Tonicity

Hypertonic

Hypotonic

Isotonic

There are equal amounts in and out of the cell, causing it to stay normal.

The cell has more water than its surroundings so all the water leaves and the cell shrivels up.

The cell has less than its surroundings, causing it to take up more. Then exploding (lysing).

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More Information

Terms for Plant Cells

Turgrid: Swollen/ inflated - the health state for a plant

Flaccid: Limp - the plant is wilted

Plasmolysis: When the cytoplasm pulls away from the cell wall casuing the cell to sink into itself.

Active Transport

Energy! ATP!

Ions, bigger molecules and polar molecules require active transport. Example: Glucose and amino acids

Goes from low to high concentration which means its movig up the concentration gradient.

ATP: Adenosine Triphosphate

Example: Sodium-Potassium PumpActively transporting sodium out of the cell and potassium into the cell

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Sodium-Potassium pump

Important Vocab

1. Membrane Potential: The difference in electrical charges across the membrane. 2. Electrochemical gradient: The diffusion gradient that is affected by both chemical and electrical force. 3. Electrogenic pump: An active transport protein that generates voltage across a membrane while pumping ions. 4. Proton pump: Uses ATP to transport hydrogen ions against its concentration gradient. 5. Cotransport: The pairing of substances, one in going "downhill" and the other going "uphill"; being transported against its concentration gradient.

Video

Exocytosis & Endocytosis

The cellular movement of larger molecules from in to out of the cell or vise versa.Exocytosis– The secretion of large molecule from the cell via a vesicle. Endocytosis– The uptake/ movement of large molecules into the cell via vesicle.

More on Endocytosis

Phagocytosis

Pinocytosis

Receptor-Mediated

Cell eating

Cell drinking

Cell drinking on a higher scale and involves cell receptors

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Any Questions?

Refrences

Pearson Text Book

https://plus.pearson.com/courses/alston54389/products/BRNT-CCD1J3NNHS/pages/4dbde220-7457-11ed-8790-cc574df4cc11?key=103311836120144487010262023

YouTube Playlist

https://www.youtube.com/playlist?list=PLo2_2YFgtuaq539RyjUW7owuPUJJey942

Activity!

Making a Fluid Mosaic Model: 1. You will take a 3 different peices of colored paper and weave them together. Represent the mosaic like formation of the proteins. 2. Take the sponges and glue them together the represent the fluidity of the bilayer.

Any questions?

Post-Test Time!

Get your electronics back out. Scan the QR code and begin.

https://quizizz.com/admin/quiz/6564c1f1da3022e88cab17d8/startV4?fromBrowserLoad=true

Pre-Test Time

Quizzes QR Code:

https://quizizz.com/admin/quiz/6564c1f1da3022e88cab17d8/startV4?fromBrowserLoad=true

• Test what you might know
• See what you don't
• This is no pressure!

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Do you have any questions?

Activity!

Making a Fluid Mosaic Model: 1. You will take a 3 different peices of colored paper and weave them together. Represent the mosaic like formation of the proteins. 2. Take the sponges and glue them together the represent the fluidity of the bilayer.