SECTION B CELL Flashcards
What is a cell?
The basic structural and functional unit of living organisms.
Where are organelles found?
within the cytoplasm
What 4 structures are found in both plant and animal cells?
- cell membrane or plasma membrane
- cytoplasm
- nucleus
- mitochondria
What 3 structures are found in plant cells only?
- cell wall made of cellulose
- chloroplasts
- a large vacuole
Can you compare plant and animal cell?
- Have cell wall made of cellulose.
Does not have cell wall. - Have chloroplasts containing chlorophyll.
Does not have chloroplasts containing chlorophyll. - Have one large central vacuole.
Vacuoles are small and scattered through the cytoplasm. - Contains starch grains as food store.
Contains glycogen granules as food. store. - Have a regular shape, usually round, square or rectangular.
Can have a great variety of different shapes.
What are microbes?
Microbes are microorganisms that include all members of the Prokaryotae kingdom and many members of the Protoctista Kingdom (ameoba) and some members of the Fungi kingdom (yeast).
Can you discuss cell specialization?
The body of a unicellular organism consists of one unspecialized cell. This cell carries out all essential life processes.
The body of a multicellular organism is composed of many cells. To enable multicellular organisms to carry out all essential life processes efficiently, cells become specialized to carry out specific functions, example muscle cells contract to bring about movement and mesophyll cells in leaves carry out photosynthesis. By becoming specialized, cells are better able to carry out their specific functions.
Cells specialized to carry out a particular function work together in groups called tissues. Different tissues are then grouped together to form specialized organs which may perform one or more functions, example the skin is composed of epithelial, connective and nervous tissue and the leaves of plant are composed of epidermal and vascular tissues. Organs work together in organ systems, example the digestive, nervous and blood vascular system in animals and transpiration and translocation system in plants. Systems work together in an organized way to form a multicellular organism.
What is a tissue?
A tissue is a group of cells that work together to perform a particular function.
cell membrane?
- Separates the interior of all cells from the outside environment which protects the cell from its environment.
- The cell membrane consists of a lipid bilayer that is semipermeable. The cell membrane regulates the transport of materials like nutrients entering and materials like waste exiting the cell.
- Active transport
Reference to the cell membrane as a differentially permeable membrane, contrast with cell wall which is freely permeable.
cell wall?
Freely permeable made of cellulose.
- Supports and protects the cell.
- Gives the cell its shape.
- It controls intercellular transport. Turgor pressure.
chloroplasts and mitochondria?
Organelles that capture and release energy. These 2 organelles have their own DNA.
Chloroplasts are disc-shaped organelles.
- Contain chlorophyll.
- Site where photosynthesis occurs.
Mitochondria are rod-shaped organelles
- Generate chemical energy needed to power cell reactions - produce ATP.
- Site where respiration occurs.
- Contain respiratory enzymes.
starch grains?
food store
plant vacuole?
Large membrane-bound organelle containing cell sap.
- Supports the cell when turgid.
- May store food or cell waste.
animal vacuole?
Small and membrane-bound sacs.
- Important in endocytosis and exocytosis.
- Store waste products and prevents cell contamination.
contractile vacuole?
Saclike osmoregulatory organelle of amoeba.
Controls the intracellular water balance by accumulating and expelling excess water out of the cell, allowing cells to survive under hypotonic stress as in pond water.
nuclear membrane?
- Separates the nucleus from the cytoplasm.
2. Controls what goes in and out of the nucleus.
nucleus?
A double membrane-bound organelle that controls the activities of the cell.
- Contains the genetic information of the cell in the form of DNA.
- Controls the characteristics and functioning of the cell (growth and metabolism).
- Site of RNA production.
nucleoid?
A single, long and coiled loop of DNA. Controls all cellular activities.
cytoplasm?
Jelly-like fluid inside the cell.
- Holds and supports the organelles of the cell providing a a platform upon which organelles can operate within the cell.
- Protects organelles from damage.
- Meditates the entry and exit of substances, example cellular contents between the plasma membrane and nucleus, including cytosol.
glycogen granules?
food store
capsule?
A slimy outer layer that surrounds the cell walls of some bacteria, protecting the cell surface and sometimes helping to glue the cell to surfaces.
plasmid?
Small, circular piece of DNA located in the cytoplasm of many bacteria.
flagellum?
Long, whip-like structure.
Aids in movement.
pseudopodium?
A cellular extension of amoeboid cells.
- Used to engulf food for feeding.
- Aid in movement.
How can substances move into and out of cells and from cell to cell?
- diffusion
- osmosis
- active transport
What is diffusion?
Diffusion is the net movement of particles from an area of higher concentration to an area of lower concentration until the particles are evenly distributed.
The particles move down a concentration gradient.
Can you list 3 reasons why diffusion is important?
- Oxygen for aerobic respiration moves into organisms through gaseous exchange surfaces and into cells by diffusion. Oxygen produced in photosynthesis moves out of plant cells by diffusion.
- Carbon dioxide produced in aerobic respiration moves out of cells and out of organisms through gaseous exchange surfaces by diffusion. Carbon dioxide used in photosynthesis moves into leaves and plant cells by diffusion.
- Glucose and amino acids produced in digestion are absorbed through cells in the ileum and capillary walls and into the blood by diffusion.
What is osmosis?
Osmosis is the movement of water molecules through a differentially permeable membrane from a solution containing a lot of water molecules (a dilute solution or water) to a solution containing fewer water molecules (a concentrated solution).
Can you list 5 reasons why osmosis is important?
Osmosis is a special form of diffusion.
- All cells are kept hydrated by water moving into them by osmosis.
- Plant cells are kept turgid by water moving into them by osmosis. This causes non-woody stems to stand upright and keeps leaves firm.
- Water is kept moving through plants by osmosis occurring in the cells of roots and leaves. This ensures that leaves get water for photosynthesis.
- The size of stomatal pores is regulated by osmosis in the guard cells. This control the loss of water from the leaves of plants.
- Water is reabsorbed into the blood from. the filtrate in the kidney tubule by osmosis. This prevents the body from losing too much water.
What is active transport?
During active transport particles move through membranes against a concentration gradient. Energy produced in respiration is used to move the particles through the membranes from areas of lower concentration to areas of higher concentration. Active transport allows cells to accumulate high concentrations of important substances like glucose, amino acids and ions.
Can you list 4 reasons why active transport is important?
- Mineral ions move from the soil into plant roots by active transport.
- Sugars produced in photosynthesis move into the phloem in leaves by active transport.
- Some of the glucose and amino acids produced in digestion are absorbed from the ileum into the blood by active transport.
- Useful substances are reabsorbed from the filtrate in the kidney tubules into the blood by active transport.
In multicellular organisms, cells become different from one another in order to carry out particular functions. This is called
(a) specialization
(b) adaptation
(c) evolution
(d) selection
(a) specialization
Which of the following BEST describes the nucleus of a cell?
(a) It is not permeable.
(b) It contains starch grains.
(c) It contains mitochondria.
(d) It stores genetic information in the form of DNA.
(d) It stores genetic information in the form of DNA.
