Unit 1: Section 1 - Cell Structure Flashcards
Are prokaryotic cells simple or complex? Are eukaryotic cells simple or complex?</p>
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<p>Simple (e.g. bacteria) complex (e.g. plants and animals)</p>
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<p><p>What is plasmodesmata?</p></p>
<p><p>'channels' for exchanging substances with adjacent cells</p></p>
<p><p>Brief explanation of... cell surface membrane</p></p>
<p><p>A membrane made up of mainly proteins and lipids. It regulates the movement of substances in and out of the cell. Also has receptor molecules to respond to chemicals like hormones.</p></p>
<p><p>...Cell wall</p></p>
<p><p>Rigid structure that surrounds plant cells. Made of mainly cellulose. Provides support to plant cells.</p></p>
<p><p>...Nucleus</p></p>
<p><p>Large organelle surrounded by nuclear envelope, which contains pores. Contains chromatin and nucleolus. Chromatin controls the cells activities. The nucleolus makes ribosomes</p></p>
<p><p>...Lysosome</p></p>
<p><p>A round organelle surrounded by a membrane with no clear internal structure. Contains digestive enzymes, used to digest invading cells or to break down worn out components of the cells.</p></p>
<p><p>...Ribosome</p></p>
<p><p>Small organelle, either floats free in cytoplasm or attached to rough endoplasmic reticulum. Site where proteins are made</p></p>
<p><p>...Rough endoplasmic reticulum</p></p>
<p><p>System of membranes enclosing a fluid-filled space. The surface is covered with ribosomes. Folds and processes proteins that have been made at the ribosomes.</p></p>
<p><p>...Smooth endoplasmic reticulum</p></p>
<p><p>Similar to RER but no ribosomes. Synthesises and processes lipids.</p></p>
<p><p>...Vesicle</p></p>
<p><p>Small fluid filled sac in cytoplasm. Transports substances in and out of the cell and between organelles. Made at golgi apparatus or endoplasmic reticulum, or at cell surface.</p></p>
<p><p>...Golgi apparatus</p></p>
<p><p>Group of fluid-filled flattened sacs. Processes and packages new lipids and proteins. Also makes lysosomes.</p></p>
<p><p>...Mitochondria</p></p>
<p><p>Have a double membrane. Inner one folded to make structures called cristae. Inside is the matrix which contains enzymes involved in respiration.</p></p>
<p><p>...Chloroplast</p></p>
<p><p>Where photosynthesis takes place.</p></p>
<p><p>...Centriole</p></p>
<p><p>Small hollow cylinders containing ring of microtubules. Involved with separation of chromosomes during cell division.</p></p>
<p><p>...Cilia</p></p>
<p><p>Small, hair like substances found of surface membrane of some animal cells. The microtubules allow the cilia to move. This movement is used to move substances along the cell surface.</p></p>
<p><p>...Flagellum</p></p>
<p><p>Found on eukaryotic cells. Like cilia but longer. The microtubules contract to make the flagellum move. They are used to propel cells forward.</p></p>
<p><p>What is the difference in proteins made by the ribosomes on the RER and free floating ribosomes?</p></p>
<p><p>Ribosomes on RER make proteins that are excreted or attached to the cell membrane. Free floating ribosomes make proteins that stay in the cytoplasm.</p></p>
<p><p>How does a protein made at the RER get to the cell surface?</p></p>
<p><p>They are folded and processed at the RER
They are then transported to the golgi apparatus in vesicles
At the golgi apparatus the proteins may undergo further processing
The protein enters more vesicles to be transported around the cell, some may go to the cell surface</p></p>
<p><p>What is the cytoskeleton?</p></p>
<p><p>A network of protein threads running through the cytoplasm.</p></p>
<p><p>What are the cytoskeletons four main functions?</p></p>
<p><p>- Support the cells organelles, keeping them in position
- Strengthen the cell and maintain its shape
- Transport materials within the cell
- Can cause the cell to move</p></p>
What is magnification?
How much bigger the image is than the specimen. (length of image divided by length of specimen)
What is resolution?
How well a microscope distinguishes between two points that are close together.
What are the two types of microscopes?
Light and electron
What is light microscopes maximum resolution and magnification?
0.2 micrometres and x1500
What are the two types of electron microscopes?
Transmission and scanning
How does a transmission electron microscope work?
Uses electromagnets to focus a beam of electrons, which is then transmitted through the specimen. Can only be used on thin specimens.
How does a scanning electron microscope work?
Scan a beam of electrons across the specimen. Gives a 3-D image but in lower resolutions that TEM
What are the maximum resolution and magnification for TEMs?
Resolution - 0.0001 micrometres
Magnification - more than x1,000,000
What are the maximum resolution and magnification for SEMs?
Resolution - 0.005 micrometres
Magnification - usually less than x1,000,000
Why do you need to stain your sample?
In light microscopes and TEMs the beam of light/electrons passes through the object being viewed. If your sample is transparent the light rays/electrons will just pass straight through and the whole thing will look white.
What is the difference when staining between light microscopes and TEMs?
Light microscopes use some kind of dye
TEMs use heavy metals such as led
