Chapter 7 - Cell structure and functions- Biology

Cell
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The Cell Theories
1. All organisms are composed of one or more cell.
2. The cell is the basic unit of organization of all organisms
3. All cells come from preexisting cells.
What are the differences between the eukaryotic and prokaryotic cell?
Eukaryotic can be single-celled or multicellular, they have a nucleus, their DNA is held within the nucleus, and they have organelles. Prokaryotic cells do not have a nucleus, they have no organelles, they are ALWAYS single-celled, and the DNA floats freely around the cell.
What is the role of the cell nucleus?
It contains nearly all the cell's DNA and, with it, the coded
instructions for making proteins and other important molecules.
The eukaryotic cell can be divided into two major parts:
The nucleus and the cytoplasm
Many cellular structures act as if they are specialized organs called ______
Organelles
The nucleus is surrounded by the _________________ ; composed of two membranes
Nuclear envelope
The nuclear envelope is dotted with thousands of _____________________, which allow material to move into and out of the nucleus.
Nuclear pores
Chromosomes contain the _____ that is passed from one generation of cells to the next.
Genetic information
Most of the time, the threadlike chromosomes are spread throughout the nucleus in the form of _____
Chromatin
Most nuclei also contain a small, dense region known as _____________________
Nucleolus
_____ store materials like water, salts, proteins, and carbohydrates.
Vacuoles
Lysosomes
are small organelles filled with enzymes that break down lipids, carbohydrates, and proteins into small molecules that can be used by the rest of the cell.
Cytoskeleton
Helps the cell maintain its shape and is also involved in
movement.
Many cells contain large, saclike, membrane-enclosed structures called _____
Vacuoles
The paramecium contains an organelle called _____
Contractile vacuole
Vesicles
membrane-enclosed structures that are used by eukaryotic cells to store and move materials between cell organelles, as well as to and from the cell surface.
Lysosomes breakdown ___, ___, and ___
Lipids, carbohydrates, and proteins
Eukaryotic cells are given their shape and internal organization by a network of protein filaments known as the _____
Cytoskeleton
_____ and _____ are two of the principal protein filaments that make up the cytoskeleton.
Microtubules and Microfilaments
Microfilaments are threadlike structures made up of a protein called _____
Actins
Microtubules are hollow structures made up of proteins known as_____
Tubulins
_____ are located near the nucleus and help to organize cell division.
Centrioles
What is the pattern that Microtubules are arranged in?
"9 + 2"
Proteins are assembled on _____.
Ribosomes
Ribosomes
Small particles of RNA and protein found throughout the cytoplasm in all cells.
Eukaryotic cells contain an internal membrane system known as the _____
Endoplasmic reticulum
The portion of the ER involved in the synthesis of proteins is called _____
Rough endoplasmic reticulum
In many cells, the smooth ER contains collections of _____ that perform specialized tasks, including the synthesis of membrane lipids and the detoxification of drugs.
Enzymes
a stack of flattened membranes
Golgi apparatus
The Golgi apparatus _____ as well as other materials from the ER for storage in the cell or release outside the cell.
modifies, sorts, and packages proteins
Chloroplasts capture the energy from sunlight and convert it into food that contains chemical energy in a process called ____________________________.
Photosynthesis
_____ are the biological equivalents of solar power plants.
Chloroplasts
Inside the organelle are large stacks of other membranes, which contain the green pigment called _____
Chlorophyll
_____ are the power plants of the cell
Mitochondria
What is the function of the cell membrane?
The cell membrane regulates what enters and leaves the cell and also protects and supports the cell.
Many cells, including most prokaryotes, also produce a strong supporting layer around the membrane known as a _____
Cell wall
What is the main function of the cell wall?
To provide support and protection for the cell.
Cell walls lie outside the cell membrane and most are porous enough to allow _____ and certain other substances to pass through easily.
Water, oxygen, carbon dioxide,
The composition of nearly all cell membranes is a double-layered sheet called a ___________________________________ gives cell membranes a flexible structure and forms a strong barrier between the cell and its surroundings.
Lipid bilayer
The fatty acid portions of such a lipid are __________________ while the opposite end of the molecule is __________________________
Hydrophobic, hydrophilic
Because so many different kinds of molecules make up the cell membrane, scientists describe the cell membrane as a _____
Fluid mosaic
If a substance is able to cross a membrane, the membrane is said to be _____
Permeable
What does Selectively permeable mean?
It Means that some substances can pass across them and others cannot.
What is passive transport?
The movement of materials across the cell membrane without using
cellular energy is called passive transport.
The process by which particles move from an area of high concentration to an area of lower concentration is known as __________________________
Diffusion
Diffusion depends upon _____
Random particle movement
The movement of materials across the cell membrane without using cellular energy is called _____
Passive transport
Molecules that cannot directly diffuse across the membrane pass through special protein channels in a process known as _____
Facilitated trasnport
The inside of a cell's lipid bilayer is _____
Hydrophobic
Many cells contain water channel proteins, known as _____
Aquaporins
The movement of water through cell membranes by _____ is an extremely important biological process.
Facilitated diffusion
_________________ is the diffusion of water through a selectively permeable membrane.
Osmosis
When the concentration is the same on both sides of the membrane, the two solutions will be _____
Isotonic
Hypertonic solution
A solution that has a higher concentration of solutes than another.
Hypotonic solution
A solution in which the concentration of solutes is less than that of the cell that resides in the solution.
The net movement of water out of or into a cell exerts a force known as _____
Osmotic pressure
Cells placed in _____ solution neither gain nor lose water.
Isotonic
In a _____, water rushes out of the cell, causing animal cells to shrink and plant cell vacuoles to collapse.
Hypertonic solution
What is active transport?
The movement of materials against a concentration difference is known as active transport.
The active transport of small molecules or ions across a cell membrane is generally carried out by _____ that are found in the membrane itself.
Transport proteins or protein pumps
Larger molecules and clumps of material can also be actively transported across the cell membrane by processes known as _____
Bulk transport
Endocytosis
Is the process of taking material into the cell by means of infoldings, or pockets, of the cell membrane.
Two examples of endocytosis are _____and _____
Phagocytosis and pinocytosis
In _____ extensions of cytoplasm surround a particle and package it within a food vacuole.
Phagocytosis
Engulfing material in this way requires a considerable amount of energy and, therefore, is a form of _____
Active transport
Pinocytosis
A type of endocytosis in which the cell ingests extracellular fluid and its dissolved solutes.
Many cells also release large amounts of material from the cell, a process known as _____
Exocytosis
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