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24 Cards in this Set
- Front
- Back
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Prokaryotic cells
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in bacteria. They have a simple structure (no nucleus or organelles). They are small (1 - 5 micrometers across). Usually have an external cell wall.
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Eukaryotic cells
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in plants, fungi, animals. The DNA is organized into chromosomes in the nucleus. They have specialized organelles and are larger (10 - 50 micrometers across).
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Light microscopes
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focus light on the specimen. Advantages: living cells, color, portable, cheap. Disadvantage : magnification only up to 1000.
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Electron microscopes
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focus a beam of electrons on the specimen. Advantage : high magnification (up to 1 million )Disadvantages : dead cells, black/white, not portable, expensive.
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Why are cells so small?
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They need to keep a large surface area compared to volume.
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Cells consist of :
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membrane, nucleus and cytoplasm.
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Nucleus:
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roughly 5 micrometers across. It contains genes (DNA) arranged in chromosomes, and is surrounded by nuclear membrane which has pores.
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The nucleolus
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(inside the nucleus) produces ribosomes.
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Cytoplasm
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contains many organelles
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Ribosomes
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are made of RNA and protein. Ribosomes use RNA to produce proteins.
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ER (Endoplasmic reticulum)
Rough ER |
a series of membranes with ribosomes. It produces new membranes.
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ER (Endoplasmic reticulum) Smooth ER |
membranes without ribosomes. It produces lipids. It also detoxifies chemicals (in the liver). It also stores calcium (in the muscles).
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Golgi body |
It is roughly 3 micrometers across. It packages and sends off chemicals. The cis face receives chemicals. The trans face dispatches chemicals to a certain area. |
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Lysosomes
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are produced by the Golgi body. They contain digestive enzymes to digest food brought in by phagocytosisor old organelles.
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Apoptosis
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programmed cell death ( cell suicide ): for example the tail of a tadpole is reabsorbed when it turns into a frog.Tay Sachs disease is a fatal genetic disease (the lysosomes do not work).
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Vacuoles : Animals
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food vacuoles hold food brought by phagocytosis (only in single celled animals).
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Vacuoles: Plants |
torage vacuoles hold water, minerals, poison (to deter herbivores). |
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Peroxisomes |
contain enzymes that produce hydrogen peroxide. They are used in breaking down fats. |
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Mitochondria |
They are roughly 3 micrometers across.They have a smooth outer membrane, and folded inner membrane. Mitochondria contain DNA, RNA, ribosomes, proteins.They may have evolved from early bacteria. Mitochondria are inherited only from your mother. Enzymes on inner membrane produce ATP ( energy) |
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Chloroplasts |
only found in plants. They are roughly 3 micrometers across. They have two smooth membranes. Chloroplasts contain DNA, RNA, ribosomes, proteins. Stacks of inner membrane called grana contain chlorophyll. The liquid stroma surrounds the grana. Chloroplasts produce carbohydrate by photosynthesis. |
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Cytoskeleton |
controls the shape, and movement, of the cell. It consists of microtubules and microfilaments. |
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Microtubules |
are 25 nanometers diameter. They are made of tubulin ( protein ) and they support the cell.In animals they can form cilia and flagella ( 9 + 2 arrangement |
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Microfilaments |
7 nanometers diameter. They are made of actin (protein). In animals they form muscles. In plants they cause cyclosis (cytoplasmic streaming) |
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Cell wall |
only in plants. It is made of cellulose. It stops the cell from bursting. |
