Chapter 7: Cell Structure and Function

Active transport

The movement of particles from an area of lower concentration to an area of higher concentration across the cell membrane using energy

Golgi apparatus

An organelle in cells that modifies, sorts, and packages proteins and other materials from the endoplasmic reticulum for storage in the cell or release outside the cell

Homeostasis

Relatively constant internal physical and chemical conditions

Microtubules

Are like thin, hollow pipes made up of proteins known as tubulins

Lysosome

The cell organelle that breaks down lipids, carbohydrates, and proteins into small molecules that can be used by the rest of the cell

Endocytosis

The process of taking material into the cell through a pocket of the cell membrane that folds into the cell

Microscope

Gives you a larger view of something very small, such as a cell

Microfilaments

Threadlike structures made up of a protein called actin that supports the cell and helps some cells move

Eukaryotes

Cells that enclose their DNA in nuclei

Ribosomes

Cell organelles consisting of RNA and proteins found throughout the cytoplasm in a cell; are the site of protein synthesis

Nucleus

The _______ is a structure that contains the cell's genetic material in the form of DNA and controls many of the cell's activities

cellular junctions

In order to communicate, certain cells form connections, or ________, to neighboring cells some of which hold cells together firmly, and others that allow small molecules carrying chemical messages or signals to pass from one cell to the next.

stiff layer

All cells are surrounded by a barrier known as the cell membrane, and many cells also have a(n) ________ around the membrane known as a cell wall.

Single

________- celled organisms include both prokaryotes and eukaryotes.

Cytoskeleton

The network of protein filaments in a eukaryotic cell that gives the cell its shape and internal organization and is involved in movement

chloroplasts

Inside the ________ are large stacks of other membranes that hold the green pigment chlorophyll.

Endoplasmic reticulum

The internal membrane system found in eukaryotic cells and the place where lipid components of the cell membrane are assembled

Diffusion

The process by which molecules of a substance move from an area of higher concentration to an area of lower concentration

nuclear envelope

The ________ is dotted with thousands of holes that allow material to move into and out of the nucleus.

Exocytosis

Many cells release large amounts of material through a process known as _______

Osmosis

The diffusion of water through a selectively permeable membrane

Protein synthesis

________ occurs on ribosomes- a cell organelle consisting of RNA and protein found throughout the cytoplasm in a cell.

Small molecules

________ or ions move across a cell membrane through the work of protein pumps found in the membrane.

Prokaryotes

Cells that do not have nuclei and their DNA is not separated from the rest of the cell

higher concentration

When the solution outside of the cell has a(n) ________ than the inside solution, the outside solution is hypertonic.

Plants

________ and some other living things have chloroplasts- organelles found in cells of plants and some other organisms that capture the energy from sunlight and convert it into chemical energy in a process called photosynthesis.

Vacuoles

Large, membrane sacs that store materials like water, salts, proteins, and sugars

Light microscopes

Use glass lenses to focus light and magnify the object

Robert Hooke

In 1665, ________ used a microscope to look at thin slices of cork from plants that seemed to be made of many tiny, empty boxes; Hooke called these boxes "cells, "and they are the basic units of life.

Tissue

A group of similar cells that perform a particular function

lower concentration

When the solution outside of the cell has a(n) ________, it is hypotonic.

Scanning electron microscopes

In ________, a beam of electrons is scanned over the surface of an object to give a three-dimensional image of the object's surface

nuclear envelope

The nucleus is surrounded by a(n) ________ made up of two membranes.

chloroplasts

Both ________ and mitochondria have their own genetic information in the form of small DNA molecules.

Microtubules

Help the cell keep its shape and are also found in hairlike organelles called cilia and flagella

endoplasmic reticulum

Many ribosomes are free in the cytoplasm, while others are attached to the ________.

osmosis

In ________, as in all diffusion, molecules move from higher concentrations to lower concentrations- lower concentrations of water.

chloroplasts

Like ________, mitochondria are surrounded by two membranes- an outer membrane and an inner membrane.

Despite their differences, at some point in their lives, all cells have DNA

the molecule that carries genetic information; all cells are also surrounded by a thin, flexible barrier called a cell membrane

There are two main kinds of cells

one kind has a nucleus, and the other does not

Even though they are simpler than eukaryotes, prokaryotes do all the activities that living things must do to be called "alive

" they grow, reproduce, respond to the environment, and, in some cases, glide along surfaces or swim through liquids

Its easy to divide each eukaryotic cell into two major parts

the nucleus and the cytoplasm (the fluid portion of the cell outside the nucleus)

Many structures in plant and animal cells act like specialized organs and are known as organelles

specialized structures that perform important cellular functions within a eukaryotic cell

Protein synthesis occurs on ribosomes

a cell organelle consisting of RNA and protein found throughout the cytoplasm in a cell

Rough ER

Proteins are made on the rough ER; it is called "rough" because the ribosomes on its surface make it bumpy

Smooth ER

The smooth ER is called "smooth" because there are no ribosomes on its surface; in many cells, the smooth ER has groups of enzymes that make membrane lipids and get rid of toxins, such as drugs

Plants and some other living things have chloroplasts

organelles found in cells of plants and some other organisms that capture the energy from sunlight and convert it into chemical energy in a process called photosynthesis

Nearly all eukaryotic cells, including plant cells, have mitochondria

cell organelles that convert the chemical energy stored in food into compounds that are more convenient for the cell to use

The special lipids in the cell membrane have two parts

a head and a tail

Sometimes there are differences in concentration of salts, sugars, proteins, and other dissolved molecules on one side of the cell membrane that produce a force known as osmotic pressure

the pressure that must be applied to prevent osmotic movement across a selectively permeable membrane

Cells

The basic units of life

Cell theory

States that all living things are made up of cells, that cells are the basic units of structure and function in living things, and that new cells come from existing cells

Electron microscopes

Produce even higher magnifications by using electrons instead of light

Transmission electron microscopes

Send beams of electrons through thin slices of cells and tissues

DNA

The molecule that carries genetic information

Cell membrane

A thin, flexible barrier that all cells are also surrounded by

Cytoplasm

The fluid portion of the cell outside the nucleus

Organelles

Specialized structures that perform important cellular functions within a eukaryotic cell

Nucleolus

The small, dense area in the nucleus is the _______, where ribosomes are first put together

Vesicles

Small membrane sacs that store and move materials between organelles as well as to and from the outside of the cell

Chloroplasts

Organelles found in cells of plants and some other organisms that capture the energy from sunlight and convert it into chemical energy

Mitochondria

Cell organelles that convert the chemical energy stored in food into compounds that are more convenient for the cell to use

Cell wall

A stiff layer around the cell membrane whose main job is to support, shape, and protect the cell

Lipid bilayer

A double-layered sheet that makes membranes flexible and lets them form a strong barrier between the cell and its surroundings

Permeable

If a substance is able to cross a membrane, the membrane is said to be _______ to it

Selectively permeable

Most cell membranes are _______, which means that some substances can pass across them and others cannot

Passive transport

The movement of materials across the cell membrane without using cellular energy

Facilitated diffusion

The process of diffusion in which molecules pass across the membrane through cell membrane channels

Isotonic

When the solutions inside and outside of the cell are the same, the solutions are said to be _______

Hypertonic

When the solution outside of the cell has a higher concentration than the inside solution, the outside solution is _______

Hypotonic

When the solution outside of the cell has a lower concentration, it is _______

Osmotic pressure

The pressure that must be applied to prevent osmotic movement across a selectively permeable membrane

Organ

A group of tissues that work together to perform closely related functions

Organ system

A group of organs that work together to perform a specific function