Water and the Cell Membrane

Q: What molecule takes a shape that looks like a twisted ladder? What is the real name of this shape? A: DNA. The DOUBLE HELIX looks like a twisted ladder. Quick ReviewQuick Review

Remember: Before RNA can be transcribed, the two strands of DNA must first _____________________ between the ________________ bases. Quick ReviewQuick Review nitrogen separate

Q: What are the 3 types of RNA? messenger RNA (mRNA)transfer RNA (tRNA) ribosomal RNA (rRNA) Quick ReviewQuick Review

Nucleus Endoplasmic Reticulum Golgi Apparatus Quick ReviewQuick Review 1. Where are proteins translated that will be modified or packaged? _____________________________ 2. Which organelle is responsible for actually modifying and packaging the protein? _____________________________ Endoplasmic Reticulum Golgi apparatus

glucose The entire complicated process of cellular respiration can be summed up by one chemical equation. What is the name of each molecule involved? oxygen??water carbon dioxide Quick ReviewQuick Review ??

1. Which organelle is the location for most energy conversion in animal cells? _____________________________ 2. What energy carrying molecule is created using the energy released from glucose during cellular respiration? _____________________________ The Mitochondria A T P

Name the organelles we have learned about so far: 1.Compartment containing the DNA of the cell: ___________________ 2.Compartment where special proteins are translated: ___________________ 3.Compartment where proteins are modified or packaged: ________________ 4.Compartment where energy is placed into ATP: ___________________ nucleus endoplasmic reticulum Golgi apparatus mitochondria

Each of these organelles has its own membrane to keep the correct molecules inside the organelle and the incorrect molecules outside of the organelle. Because of this, they are referred to as ____________________ organelles. membrane-bound Nucleus Endoplasmic Reticulum Golgi Apparatus vesicle

Every cell is full of an __________________ solution which contains of all of the biomolecules needed for the chemistry of life. aqueous CYTOPLASM

Q: According to your vocabulary reference sheet, what does aqueous mean? A: ____________________________________________________________ Aqueous means that it is full of water. = water

In order to understand solutions, you have to understand 2 words: Solute: _______________________________________ Solvent: ______________________________________ water salt saltwater solution The substance doing the dissolving The substance being dissolved solute solvent

Water can dissolve many things, including almost all of the biomolecules. Being in a solution allows them to float through the water and easily reach each other to carry out the chemical reactions that are a part of the cell’s _______________________. metabolism enzyme

W ATER CAN DISSOLVE SO MANY THINGS BECAUSE ITS MOLECULES ARE ___________. POLAR Molecules are formed when atoms share _________________. If they do not share them equally, then there will be a __________________ side of the molecule and a __________________ side of the molecule. Since water is polar it can dissolve everything that is polar or has a full charge. electrons positive negative δ - δ +

Because water is a _____________ solvent, it can dissolve 3 of the 4 classes of biomolecules: ______________________, ______________________, and ______________________. polar carbohydrates nucleic acids proteins

Water cannot dissolve ____________ because they are _______________. (Lipids are also known as _________.) Lipids are the main biomolecule in all of the cell’s __________________. But the membrane must be able to interact with water since water is the solvent of the solution in the cell called ____________________. To make this happen, the cell attaches a _____________________ group to the lipid to create a __________________________. lipids nonpolarfats membranes cytoplasm phosphate phospholipid Name of Molecule: _______________________ phospholipid

The phosphate group will dissolve in the water very well, while the rest of the lipid will not. Because of this, the phosphate group is _________________ to the water while the lipid is pushed away or __________________. Since cells are full of ____________ and almost always surrounded by ____________, this causes the phospholipids to arrange themselves in pairs. attracted repelled water This arrangement of phospholipids is known as a phospholipid __________________. bilayer

Q: What does the prefix bi- mean? A: __________________________ Bi- means two. Bicycles have 2 wheels. If you are bilingual, you speak 2 languages. Biannual events happen every 2 years. Bilayers have 2 layers. 12

Remember: Membranes keep the correct molecules ______________ of the cell or organelle, and they keep other molecules _______________ of the cell or organelle. However, some small molecules that necessary for life can squeeze through the lipid bilayer uncontrolled. These include the gases __________________ and ____________________________ and one of the most important molecules for the cell: __________________. inside outside oxygen carbon dioxide water

If a membrane allows molecules across, it is called a ___________________ membrane. Cell membranes only allow some molecules through, so they are called ____________________ membranes permeable semi-permeable

The process of water moving across a semi- permeable membrane is called _____________. Water moves across a cell membrane in a very predictable pattern. It moves from where it is __________________ to where it is ________________________. This means it moves from where there are fewer solutes dissolved across to the side of the membrane where there are more solutes. You can think of the water as moving to the side where water molecules need the most help dissolving a large number of _____________________. osmosis purest least pure solutes Water moves into the cell. Water moves out of the cell.

It may sound like a good thing that water can travel across the semi-permeable cell membrane without any help, but this can also be a big problem. 1.If too much water enters a cell because of osmosis, the cell can _____________ to a size that is too large and eventually it will ______________. 2.If too much water leaves a cell because of osmosis, the cell can _____________ to a size that is too small. Both of these situations will cause the cell to __________, so the movement of water is an important concern for all living things. swell burst shrink die

The picture shows a cell model and the solutions associated with it. For each of the following models, decide which will occur: 1. Water will leave the cell causing it to shrink 2. Water will enter the cell causing it to swell 3. The water level is balanced and neither will occur

swellshrinkneither

shrinkshrink swell

swellshrink swell

swellneithershrink

shrink swellswell