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Bio-Chapter 4-MHS

Structure and Function of the Cell

TermDefinition
What are the three parts of the cell theory? 1. All living things are composed of one or more cells. 2. Cells are the basic units of structure and function in an organism. 3. Cells come only from the reproduction of existing cells.
Cell The smallest unit of mattresses than can carry on all the processes of life.
Who created the cell theory? Hooke and van Leeuwenhoek
Are all cells alike? No. There are at least 200 different cell types in our bodies alone.
Do you need a microscope to see all cells? No. Some cells can be seen with your unaided eye.
Why are cells limited in size by the ratio between their outer surface and their volume? It is important to know that if a cell grows too large and the surface area becomes too small, it is difficult for the cell to get the nutrients and oxygen it needs. Nutrients and oxygen enter through the surface of the cell.
Do cells have different shapes? Yes. Cells have a variety of shapes.
Why do cells have different shapes? Cell shapes differ depending on what their duty (role) is. Nerve cells have long extensions to receive/transmit impulses. Skin cells are flat to cover the surface of the body.
Organelles A cell component that performs specific functions for the cell. Organelles maintain the life of the cell. (Compare this the "heart" in our body. It pumps blood and oxygen through our body to maintain life.) An organelle maintains the life of the cell.
Cell membrane Thin membrane surrounding a cell Organelles also each have their own membrane.
Nucleus 1. The large organelle near the center of the cell. 2. Contains most of the cell's genetic information. 3. Directs most of the cell's activities
Eukaryotes Organisms whose cells contain a membrane-bound nucleus and other organelles
Prokaryotes Unicellular (one celled) organisms that lack a membrane-bound nucleus and other organelles
What is the difference between a eukaryote and prokaryote? Eurkaryotes have a membrane-bound nucleus and prokaryotes do not. Prokaryotes are placed in a different kingdom.
Can a cell survive if it is isolated from its environment? No. Cells must take in nutrients and dispose of waste. Both actions pass through the cell membrane.
Selectively Permeable meaning? Some substances easily cross the membrane and others cannot.
What does the structure of the cell membrane depend on? the functions that the cell performs
What are cell membranes primarily made up of? lipids and protiens
What does a phospholipid molecule have? a polar "head" and two non polar "tails"
Does the head of a phospholipid orient itself away from or close to water molecules? The head of a phospholipid orients itself CLOSE to water molecules.
Does the tail of a phospholipid orient itself away from or close to water molecules? The tail of a phospholipid orients itself AWAY from water molecules.
Aqueous Watery environment that bathe cells
What parts are cells surrounded by water molecules? The outside AND inside of cells are surrounded by water. The inside of a cell is an aqueous environment.
How many layers do water molecules cause the phospholipids of the cell membrane to form? TWO layers. (A lipid bilayer) Heads point outward and tails are confined to the interior of the cell membrane.
What additional thing do eukaryotic cell membranes contain? steroids molecules. Steroid molecules fit between the tails. Cholesterol is an example of a steroid molecule in animals.
Peripheral proteins located on the interior and exterior surface of the cell membrane
integral proteins proteins embedded in the bilayer of the cell membrane
Why must cells have mechanisms for transporting molecules through the lipid bilayer? Because the cell membrane is selectively permeable
Fluid mosaic model -lipid bilayer behaves like a fluid more than a solid -lipids and proteins can move laterally within the lipid bilayer -pattern/mosiac is constantly changing
cytoplasm -lies between cell membrane and nucleus -contains the organelles of the cell
cytosol gelatin-like aqueous fluid that bathes organelles
What is the cytosol made up of? salts, minerals, and organic molecules are dissolved in the cytosol
Mitochondria -large organelles scattered throughout the cytosol -mitochondria are the sites of chemical reactions that transfer energy from organic compounds to ATP (molecule that most cells use as their main energy currency)
What is true about the amount of mitochondria in cells that need a lot of energy? The more energy a cell requires, the more mitochondria it needs,
How many membranes surround the mitochondria? Two outer membrane - smooth; a boundary between mitochondrion and cytosol inner membrane - long folds (cristae) - enlarge surface area of inner membrane
cristae inner membrane of mitochondrion -enlarge the surface area of inner membrane -proide more space for the chemical reactions that occur in the mitochondrion
Do Mitochondria have their own DNA? Yes. Mitochondrion have their own DNA. New mitochondria arise only when existing ones grow and divide.
ribosomes -the most numerous organelles in many cells. -are NOT surrounded by a membrane
What is a ribosome made up of? protein and RNA
What is the role of a ribosome? - synthesis of protein
endoplasmic reticulum -ER -system of membranous tubules and sacs -function: intracellular highway where molecules move from one part of the cell to another
What are the two types of ER (endoplasmic reticulum)? -rough endoplasmic reticulum - rough ER - covered with ribosomes -smooth endoplasmic reticulum - smooth ER 0 synthesis of steroids in gland cells , regulation of calcium levels in muscles, and breakdown of toxic substances in liver cells.
Golgi apparatus -the processing, packaging, and secreting organelle of the cell. -system of membranes
Lysosomes -small, spherical organelles that enclose hydrolytic enzymes within single membranes, DNA, RNA, viruses, and bacteria.
Are lysosomes common in animal or plant cells? Lysosomes are common in animal cells and rare in plant cells
cytoskeleton -structure to maintain shape and size in cells -network of protein strands found in the cytosol -not supported by membranes
What are the two main components of the cytoskeleton? -microfilaments and microtubules
Microfilament -threads made of protein called ACTIN that make up part of the cytoskeleton. ---Contribute to cell movement - example - muscle contraction
Microtubules -largest strands of the cytoskeleton -hollow tubes
Spindle fibers -bundles of microtubules that one together and extend across the cell when it is about to divide. -can be quite large
cilia and flagella -hairlike organelles that extend from the surface of the cell -assist in momvement
cilia -organelle that assist in cell movement -when they are short and present in large numbers they are called cilia
flagella -organelle that assist in cell movement -when they are long and less numerous on a cell they are called flagella
nucleus -most prominent structure within a eukaryotic cell -stores heredity information in its DNA -RNA copied from DNA
nuclear matrix - a protein skeleton that helps the nucleus maintain its shape
nuclear envelope a double membrane that surrounds the nucleus
chromatin a combination of DNA and protein found in the nuclear envelope
nuclear pores -small holes in the nuclear envelope -RNA makes its journey through the nuclear pores
Nucleolus the site where ribosomes are synthesized and partially assembled before they pass through the nuclear pores to the cytosol.
Plant cells have three additional kinds of structures. What are they? cell walls, vacuoles, and plastids
Cell Wall a rigid plant cell covers a plant cell and lies outside the cell membrane
vacuoles fluid-filled organelles that store enzymes an metabolic wastes in plant cells
plastids organelles that are surrounded by to membranes and contain DNA in plant cells.
chloroplast the most familiar type of plastid in plant cells. convert sun energy and contains a large amount of green pigment giving leaves a green color
thylakoids flattened membranous sacs in chloroplast (plant cell)
tissues group of cells that carry out a specific function. for example - skin, nervous tissue
organ several type of tissues that interact to perform a specific functions. example, stomach
organ system group of organs that work togther for a specific task. (digestive system - mouth, esophagus, stomach, intestines, etc.)
colonial organisms collection of genetically identical cells that live together in a closely connected group
Created by: D. Waara