Unit 99 cell transport

QUIZLET 1 Essentials: https://quizlet.com/_7cbrgw

Quizlet 2 - Additional Organelles: https://quizlet.com/_7cbvm5

Quizlet 3- Classification https://quizlet.com/_7cby57

Human Cheek (epithelial) Cells:

Topic 1 - Review of Cell Organelles

We went through this quickly as I was informed this is covered quite a bit in middle school. If that was not the case for you, please spend some additional time reviewing the material.

In this mini-unit, you should learn the functions of cell organelles and what they look like (cartoons will do). Also, know what organelles are only found in animals cells (centrioles) and which are only found in plant cells (cell walls and chloroplasts). Note that all other kingdoms have organisms with cell walls - all kingdoms except the animals kingdom. The difference is Fungi make their cell walls from a material different than the cellulose plants use. Bacteria and Archae use different materials as well.

We will also be reviewing the function of each organelle as it is used in other units. For example, we will talk more about ribosomes when we discuss protein synthesis. We will study mitochondria in more detail when we talk about cellular respiration. And centrioles when we talk about dividing the nucleus in mitosis and meiosis.

The Theory of Endosymbiosis is important in understanding how complex cells (eukaryotes) evolved from simple cells (prokaryote). There is a great deal of evidence to suggest that complex organelles, like chloroplasts and mitochondria, were once free-living bacteria that were engulfed by a larger prokaryotic cell. They stuck around inside the cells and over time they became organelles. Now they can't survive outside of a cell. But check out these videos to gather some evidence to support this theory!

What are organelles? Video to review:

Theory of Endosymbiosis:

Another explanation of endosymbiosis:

TOPIC 2 - CELL TRANSPORT - Osmosis, Diffusion and Active Transport (NOT DOING 2019-2020)

In this unit we will look at how nutrients and other materials get in and out of our cells. In the last unit, we learned that after molecules are broken down in digestion, they are transported into the blood stream where they are delivered throughout the body. This is why digestion is all about breaking them into their small building blocks! Small molecules are transported much more easily than large ones across cell membranes!

When materials (mostly molecules) leave the blood there are a few ways they can move into cells - either passively (not using energy) or actively (requiring energy). Osmosis and diffusion are both passive processes that depend on concentration gradients. For example, diffusion can only move from areas of high concentration to low concentration, so if your lungs are not taking in more oxygen than your blood already has, no more oxygen will diffuse into your blood. On the flip side, CPR works on a patient who is not breathing because even your exhaled breath has more oxygen than the blood of a person who isn't breathing at all!

Osmosis is a specific type of diffusion because it is specifically about water movement - and water movement across a selectively -permeable membrane - usually a cell membrane! What does it mean to be selectively permeable? This means some things can pass through easily while others cannot. For example, in the picture below, water molecules (H2O) are small enough to pass through the membrane but sugar molecules are much larger and therefor cannot pass. In the example below, this makes the water level rise on the right side. Why does water move at all? It is just diffusing like anything else would until it reaches equilibrium. The sugar would diffuse to the right side if it could. So in osmosis, remember, water is the particle that moves in order to reach equilibrium!

So passive transport (diffusion and osmosis) only really work if the material is a small molecule or if it has no charge. Sodium ions, for example, Na+ are just a single atom but because they have an electrical charge (as indicated by the + sign), they cannot pass through the cell membrane unless they pass through a special channel. Remember the cell membrane is mostly made of phospholipids, but these special channels are made of proteins. This is how larger molecules, like glucose, get into cells as well. This involves either facilitated diffusion -passage through a protein channel without the use of energy - or active transport, which requires energy.

Active transport has a few different types. We will mostly talk about primary active transport. This is how our blood can absorb glucose from our food and take in as much as possible. If we absorbed glucose in our blood through diffusion then we would only absorb as much as we release in our waste or feces. This is because it would only diffuse until equilibrium was reached. But if you actively transport it, you can take in more glucose. This requires energy - and like all energy used in the cell, it comes from ATP. So active transport pumps materials up their concentration gradients (from low concentrations to high concentrations) and it usually involves transport through a protein channel or a protein carrier embedded in the cell membrane.

Sometimes cells can engulf really large molecules or even an entire single cell by wrapping them in cell membrane and bringing them inside the cell. This is called endocytosis. The cell can get rid of things in a similar manner by making small transport vessels called vesicles and sending them to fuse with the cell membrane to dump their contents - called exocytosis. This is how our brain cells dump all their chemicals - or neurotransmitters. See the picture below to see how endocytosis and exocytosis work!

Results of the Diffusion lab: Which Solute is Permeable?

Cell Transport Videos:

Here's a video by the Amoeba sisters that will be a GREAT REVIEW for Friday's quiz! Cell transport and cell membranes!

Osmosis Specific video by the Amoeba Sisters:

Bozeman Science:

Explanation of hypertonic and hypotonic: https://www.youtube.com/watch?v=w3_8FSrqc-I

Cell Organelle & Cell Transport Practice Quizzes:

PRACTICE QUIZZES:

QUIZ 1 - Do all 3 and show each of your results to your teacher.

http://www.sheppardsoftware.com/health/anatomy/cell/index.htm

QUIZ 2 - Cell Transport Long Quiz -complete and show final score to your teacher - mostly Cell Transport. You shouldn't miss more than 2! https://www.quia.com/quiz/2102811.html

Quiz 3- Cell Transport Short Quiz https://www.biologycorner.com/quiz/qz_diffusion.html

QUIZ 4 - Another cell transport quiz - when they ask about water potential this is a term used to describe how much water a solution could potentially have. The more solutes you add to the solution the lower its water potential. http://www.bbc.co.uk/education/guides/zc9tyrd/test

QUIZ 5 - Quizlet: https://quizlet.com/190075819/test?prompt-with=1&limit=18&matching=on&mult_choice=on&selectedOnly=false&showImages=true&tf=on&written=0

A British Review Video -somewhat interactive - http://www.bbc.co.uk/education/guides/zc9tyrd/activity