Biology Semester 1- Cells

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Plasmolysis in a plant cell

Back 1

Water leaves the cell and because the cell wall is rigid (plant cells) the cell membrane shrinks away from the cell wall. The cell becomes flaccid (turgor pressure 0).

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Turgor in a plant cell

Back 2

Water enters the cell causing it to swell tight. A wall (turgor) pressure is generated when sufficient water has been taken up to cause the cell contents to press against the cell wall. Turgor pressure rises until it offsets further net influx of water into the cell. The rigid cell wall prevents cell rupture. Cells in this state are said to be turgid.

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hypertonic solution

Back 3

In a hypertonic solution the external water concentration is lower than the water concentration in the cell.

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Hypotonic solution

Back 4

The external water concentration is higher than the cell cytoplasm.

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ATP

Back 5

ATP is short for adenosine triphosphate; it is a high-energy molecule used for energy storage by organisms. In plant cells, ATP is produced in the cristae of mitochondria and chloroplasts.

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Cell membrane

Back 6

the thin layer of protein and fat that surrounds the cell, but is inside the cell wall. The cell membrane is semipermeable, allowing some substances to pass into the cell and blocking others.

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Cell wall

Back 7

a thick, rigid membrane that surrounds a plant cell. This layer of cellulose fiber gives the cell most of its support and structure. The cell wall also bonds with other cell walls to form the structure of the plant.

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Chlorophyll

Back 8

chlorophyll is a molecule that can use light energy from sunlight to turn water and carbon dioxide gas into sugar and oxygen (this process is called photosynthesis). Chlorophyll is magnesium based and is usually green.

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chloroplast

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an elongated or disc-shaped organelle containing chlorophyll. Photosynthesis (in which energy from sunlight is converted into chemical energy - food) takes place in the chloroplasts.

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christae

Back 10

(singular crista) the multiply-folded inner membrane of a cell's mitochondrion that are finger-like projections. The walls of the cristae are the site of the cell's energy production (it is where ATP is generated).

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cytoplasm

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the jellylike material outside the cell nucleus in which the organelles are located.

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golgi body

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(also called the golgi apparatus or golgi complex) a flattened, layered, sac-like organelle that looks like a stack of pancakes and is located near the nucleus. The golgi body packages proteins and carbohydrates into membrane-bound vesicles for "export" from the cell.

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mitochondria

Back 13

spherical to rod-shaped organelles with a double membrane. The inner membrane is infolded many times, forming a series of projections (called cristae). The mitochondrion converts the energy stored in glucose into ATP (adenosine triphosphate) for the cell.

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nuclear membrane

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the membrane that surrounds the nucleus.

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nucleolus

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an organelle within the nucleus - it is where ribosomal RNA is produced.

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nucleus

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spherical body containing many organelles, including the nucleolus. The nucleus controls many of the functions of the cell (by controlling protein synthesis) and contains DNA (in chromosomes). The nucleus is surrounded by the nuclear membrane

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photosynthesis

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a process in which plants convert sunlight, water, and carbon dioxide into food energy (sugars and starches), oxygen and water. Chlorophyll or closely-related pigments (substances that color the plant) are essential to the photosynthetic process.

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ribosomes

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small organelles composed of RNA-rich cytoplasmic granules that are sites of protein synthesis.

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Rough endoplasmic reticulum

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(rough ER) a vast system of interconnected, membranous, infolded and convoluted sacks that are located in the cell's cytoplasm (the ER is continuous with the outer nuclear membrane). Rough ER is covered with ribosomes that give it a rough appearance. Rough ER transport materials through the cell and produces proteins in sacks called cisternae (which are sent to the Golgi body, or inserted into the cell membrane).

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smooth endoplasmic reticulum

Back 20

(smooth ER) a vast system of interconnected, membranous, infolded and convoluted tubes that are located in the cell's cytoplasm (the ER is continuous with the outer nuclear membrane). The space within the ER is called the ER lumen. Smooth ER transport materials through the cell. It contains enzymes and produces and digests lipids (fats) and membrane proteins; smooth ER buds off from rough ER, moving the newly-made proteins and lipids to the Golgi body and membranes

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vacuole

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a large, membrane-bound space within a plant cell that is filled with fluid. Most plant cells have a single vacuole that takes up much of the cell. It helps maintain the shape of the cell.

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centrosome

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(also called the "microtubule organizing center") a small body located near the nucleus - it has a dense center and radiating tubules. The centrosomes is where microtubules are made. During cell division (mitosis), the centrosome divides and the two parts move to opposite sides of the dividing cell. The centriole is the dense center of the centrosome.

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lysosome/cell vesicle

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(also called cell vesicles) round organelles surrounded by a membrane and containing digestive enzymes. This is where the digestion of cell nutrients takes place.

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energy

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the ability to do work

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ATP

Back 25

adenine triphosphate; energy storing molecule

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ADP

Back 26

adenine diphosphate

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Photosynthesis

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the process that provides energy for almost all life

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Heterotroph

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organisms that do not make their own food

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autotroph

Back 29

organisms that make their own food

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Chlorophyll

Back 30

green pigment in chloroplasts that traps sunlight

Front 31

light reactions