7.2

Question 1

Cytoplasm

Answer 1

• the portion of the cell outside the nucleus
• in both prokaryotic and eukaryotic cells

Question 2

Nucleus

Answer 2

• a large membrane-enclosed structure that contains genetic material in the form of DNA and controls many of the cell’s activities
• control center
• nuclear envelope has two membranes with nuclear pores-allows materials to move into/out of nucleus
• nucleolus makes ribosomes and messenger RNA
• chromosomes carry the cell’s genetic information-most are spread throughout the nucleus in the form of chromatin

Question 3

Vacuoles

Answer 3

• store material like water, salts, proteins, and carbohydrates
• in plant cells, central vacuole is filled with liquid-increase rigidity to hold structures
• found in some unicellular organisms and in some animals
• contractile vacuole: contracting rhythmically pumps water out of the cell

Question 4

Vesicles

Answer 4

• all eukaryotic cells have them
• smaller membrane-enclosed structures
• store and move materials between cell organelles and to/from the cell surface

Question 5

Lysosomes

Answer 5

• small organelles filled with enzymes
• break down lipids, carbs, and proteins into small molecules that can be used by the rest of the cell
• involved in breaking down organelles that have outlived their usefulness
• remove “junk” like diseases

Question 6

Cytoskeleton

Answer 6

• network of protein filaments
• in eukaryotic cells
  transport materials between different parts of the cell
• involved in moving the entire cell (cilia and flagella)
• helps maintain its shape and is also involved in movement
• microfilaments and microtubules make up the cytoskeleton

Question 7

Ribosomes

Answer 7

• proteins are synthesized/assembled on ribosomes, sometimes in association with the rough endoplasmic reticulum in eukaryotes
• small particles on RNA and protein found throughout the cytoplasm in all cells
• get coded instructions from DNA

Question 8

Endoplasmic Reticulum

Answer 8

• In eukaryotic cells
• internal membrane system
• where lipid components of the cell membrane are assembled, along with proteins and other materials that are exported from the cell
• Rough endoplasmic reticulum has ribosomes on its surface while smooth ER doesn’t
  Newly made proteins leave ribosomes and are inserted in the rough ER where they may be chemically modified
• Proteins made on rough ER include those that will be released from the cell as well as many membrane proteins and proteins destined for lysosomes and other specialized locations within the cell

Question 9

Golgi Apparatus

Answer 9

• in eukaryotic cells
• proteins produced in the rough ER move on to this
• flattened stack of flattened membranes
• modifies, sorts, and packages proteins and other materials from the ER for storage in the cell and release outside the cell
• ship proteins to final destination

Question 10

Chloroplasts

Answer 10

• only in plant cells
• the biological equivalents of the solar power plants
• capture the energy from sunlight and convert it into food that contains chemical energy in a process called photosynthesis
• surrounded by two membranes
• has large stacks of other membranes that hold the green pigment chlorophyll

Question 11

Mitochondria

Answer 11

• in eukaryotic cells
• power house of the cell
• convert the chemical energy stored in food into compounds that are more convenient for the cell to use
• two membranes

Question 12

Cell Wall

Answer 12

• a barrier and strong supporting layer around the membrane
• in most cells (even prokaryotes)
• support, shape, and protect the cell
• animal cells don’t have
• cell walls are porous enough to allow water, oxygen, carbon dioxide, and other substances to pass through easily
• provide strength to help plants stand against gravity

Question 13

Cell/Plasma Membrane

Answer 13

• a thin flexible membrane
• has lipid bilayer: gives cell membranes a flexible structure that forms a strong barrier between the cell and its surroundings
• regulates what enters and leaves the cell and also protects and supports the cell
• selectively permeable

Question 14

Eukaryotic Cells

Answer 14

• cells that enclose their DNA in nuclei

Question 15

Prokaryotic Cells

Answer 15

• cells that do not enclose their DNA in nuclei

Question 16

Centrioles

Answer 16

• in animal cells
• formed from tubulins
• located near the nucleus and help organize cell division
• not in plant cells

Question 17

Organelles

Answer 17

• “little organs”

Question 18

Microfilaments

Answer 18

• threadlike structures made up of protein called actin
• form extensive network in some cells and produce a tough flexible framework that supports the cell
• help cells move
  responsible for the cytoplasmic movements that allow amoebas and other cells to crawl along surfaces

Question 19

Microtubules

Answer 19

• hollow structures made up of proteins known as tubulins
• maintain cell shape
• important in cell division, where they form a structure known as the mitotic spindle, which helps to separate chromosomes
• build projections from the cell surface known as cilia and flagella arranged in 9+2
• small cross-bridges between the microtubules in these organelles use chemical energy to pull on, or slide along, the microtubules, producing controlled movements

Question 20

Lipids

Answer 20

• hydrophilic heads are attracted to water
• hydrophobic fatty acid tails
• results in lipid bilayer
• head is exposed to outside of the cell
• fatty acid tails form and oily layer inside of membrane that keeps water out
• carbs are attached to many of the proteins embedded in the lipid bilayers
• proteins float among lipids = fluid mosaic model