39 terms

Chapter 7 Cell Structure and Function

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cell
collection of living matter enclosed by a barrier that separates the cell from its surroundings; basic unit of all forms of life
cell theory
idea that all living things are composed of cells, cells are the basic units of structure and function in living things, and new cells are produced from existing cells
nucleus
in cells, structure that contains the cell's genetic material (DNA) and controls the cell's activities; the "brain" of the cell; Surrounded by a double membrane (nuclear membrane)
eukaryote
organism whose cells contain nuclei
prokaryote
unicellular organism lacking a nucleus
organelle
specialized structure that performs important cellular functions within a eukaryotic cell; Membrane-bound organelles are found only inside eukaryotic cells
cytoplasm
material inside the cell membrane—not including the nucleus; consists of Cytosol (fluid) and Organelles; semiliquid portion of the cell
nuclear envelope
layer of two membranes that surrounds the nucleus of a cell; Separates nucleus from rest of cell; Double membrane; Has pores (holes in it)
chromatin
granular material visible within the nucleus; consists of DNA tightly coiled around proteins; Once it is tightly coiled there are visible Chromosomes
nucleolus
small, dense region within most nuclei in which the assembly of proteins begins
ribosome
small particle in the cell on which proteins are assembled; made of RNA and protein; Found attached to rough ER or floating free in cytoplasm; Produced in a part of the nucleus called the nucleolus
endoplasmic reticulum
internal membrane system in cells in which lipid components of the cell membrane are assembled and some proteins are modified; Helps move substances within cells
• Network of interconnected membranes (part of transport system)
Golgi apparatus
stack of membranes in the cell that modifies, sorts, and packages proteins from the endoplasmic reticulum; Vesicles pinch off and are carried through the cytoplasm to other parts of the cell, or are excreted from the cell; Packaging & shipping station of cell
• Involved in synthesis of plant cell wall
lysosome
cell organelle filled with enzymes needed to break down certain materials in the cell, rare in plant cells
vacuole
cell organelle that stores materials such as water, salts, proteins, and carbohydrates
mitochondrion
cell organelle that converts the chemical energy stored in food into compounds that are more convenient for the cell to use (ATP); the "Powerhouse" of the cell because they make energy for the cell; Cells requiring more Energy, such as muscle cells, contain more mitochondria than other cells. Mitochondria also contain their own strand of DNA; Bound by a double membrane
• Break down fuel molecules (cellular respiration)
- Glucose
- Fatty acids
• Release energy - ATP
chloroplast
organelle found in cells of plants and some other organisms that captures the energy from sunlight and converts it into chemical energy (photosynthesis); Contains the green pigment chlorophyll; Bound by a double membrane; Inside are stacked, flat
Disks of membrane.
cytoskeleton
Protein fibers that support and give shape to a cell,
• involved in organelle movement throughout cell,
• chromosome movement during cell division
• and large cell movements (cell motility and cytokinesis)
3 Groups of Fibers classified according to size:
- Microtubules (thickest)
- Intermediated filaments (middle sized)
- Microfilaments (thinnest)
centriole
one of two tiny cylindrical structures located in the cytoplasm of animal cells near the nuclear envelope; Made of microtubules
• During mitosis (cell division), Centrioles help the chromosomes line up and separate
Cell Wall
Provide support and protection; Found outside the cell membrane; Found in plants, fungi, & many protists; (NOT Animals cells) [Also in prokaryotes]
Cell Membrane
All Cells; Also called the plasma membrane-surrounds the cell and its cytoplasm - "Holds the cell together"; The cell membrane is selectively permeable-- Allowing certain materials to enter and keeping others out --"THE GATEKEEPER"
Plasma Membrane AKA Cell Membrane
Contains cell contents
•Structure - phospholipid bilayer with embedded proteins
•Function - isolates cell contents, controls what gets in and out of the cell, receives signals
DNA
Hereditary material
• Chromosomes - DNA
- Proteins
- Form for cell division
- most of time in form of Chromatin
Rough ER
Ribosomes attached to surface
- Manufacture proteins
- Not all ribosomes attached to rough ER
• Rough ER modifies proteins from ribosomes
Smooth ER
Has No attached ribosomes
• Has enzymes that help build molecules:
- Carbohydrates
- Lipids
Golgi Apparatus Function
1.. Molecules come in vesicles
2. Vesicles fuse with Golgi membrane
3. Molecules may be modified by Golgi
4. Molecules pinched-off in separate vesicle
5. Vesicle leaves Golgi apparatus
6. Vesicles may combine with plasma membrane to secrete contents
Lysosomes
- membrane-bound vesicles
containing digestive enzymes - from Golgi
• Found in the cytoplasm, they are membrane-bound spheres.
Their function is to recycle materials by breaking down
worn-out parts of a cell into smaller units.
Vacuoles
Mostly in Plants (called Central Vacuole); some animals "the storage unit" (in animal cells--smaller, more commonly used to temporarily store materials or in movement); Stores water;provides support
Cilia
involved in cellular
movement
• composed of microtubules
short, numerous, complex
Flagella
involved in cellular
movement
• composed of microtubules
longer, fewer, less complex
Robert Hooke
(1665)
- Observed sliver of cork in microscope - Saw "row of empty boxes"
- Coined the term cell
Anton van Leeuwenhoek
Observed pond water in microscope; First to see tiny living organisms
Compound Light microscope
Can observe living cells in true color
• Magnification of up to ~1000x
Electron Microscopes
Preparation needed kills the cells
• Works in a vacuum (no air) environment
• Images are black and white - may be
colorized
• Magnification up to ~100,000x
• Transmission electron microscope (TEM)
• 2-D image - (inside cells)
• Scanning electron microscope (SEM)
• 3-D image - (surface of cells or organelles
Scanning Probe Microscopes
Scans cells using a computer controlled laser
beams
• Works in ordinary air
• Only microscope that can see the largest molecule: DNA
• Magnification up to >300,000x
All Cells have
• an outermost plasma membrane
• genetic material in the form of DNA
• cytoplasm with ribosomes
Matthais Schleiden
German botanist; In 1838, he concluded that all plants were made of cells
Theodor Schwann
German biologist; In 1839, discovered all animals are made of cells
Rudolf Virchow
German physician; In 1855, concluded that new cells could be produced only from the division of existing cells
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