Bio Chapter 4

Question 1

Cell theory

Answer 1

Living organisms are made up of cells, they are the basic structural/organization unit of all organisms, and that all cells come from pre-existing cells

Question 2

Basic features of ALL cells

Answer 2

Plasma membrane - selective barrier encasing cytoplasm
Cytosol - semifluid portion of cytoplasm
Chromosome(s) - carry genes
Ribosomes - make proteins

Question 3

Prokaryotes

Answer 3

No nucleus - DNA is in nucleoid
No membrane bound organelles
Cytoplasm is bound by plasma membrane
Divide by binary fission

Question 4

Eukaryotes

Answer 4

DNA is in membrane bound nucleus
Has membrane bound organelles
Cytoplasm is in the region between the plasma membrane and nucleus
Usually much larger than prokaryotic cells
Divide by mitosis
Has internal membranes that divide cells in compartments - double layer of phospholipids and other lipids

Question 5

Endomembrane system

Answer 5

Regulates protein traffic and performs metabolic functions in the cells
Consists of:
Nuclear envelope
Endoplasmic reticulum
Golgi apparatus
Lysosomes
Vacuoles
Plasma membrane

Question 6

DNA

Answer 6

Organized into chromosomes
Each chromosome contains one DNA molecule associated with protein (chromatin)

Question 7

Nucleus

Answer 7

Contains most of the cell’s genes
Enclosed by the nuclear envelope - double membrane, each lipid bilayer

Question 8

Nucleolus

Answer 8

Site of ribosomal RNA (rRNA) synthesis

Question 9

Pores

Answer 9

Lined with a structure called pore complex - Regulates entry and exit of molecules

Question 10

Nuclear lamina

Answer 10

Lines nuclear site of envelope
Composed of proteins
Maintains shape of nucleus

Question 11

Ribosomes

Answer 11

Made of rRNA and protein
Carry out protein synthesis in 2 locations - Cytosol: free ribosomes
- ER or nuclear envelope: bound ribosomes

Question 12

Smooth ER

Answer 12

No ribosomes
Synthesize lipids
Metabolize carbohydrates
Detoxifies drugs and poisons
Stores calcium ions

Question 13

Rough ER

Answer 13

Has bound ribosomes
Secretes glycoproteins - covalently bonded to carbs
Distribute transport vesicles - secretory proteins surrounded by membranes
Membrane factory for the cell

Question 14

ER

Answer 14

More than half of total membrane in many eukaryotic cells
Continuous with nuclear envelope

Question 15

Golgi apparatus

Answer 15

Flattened membranous sacs of cisternae
Modifies products of the ER
Manufactures certain macromolecules
Sorts and packages materials into transport vesicles

Question 16

Lysosomes

Answer 16

Sites of intracellular digestion (can also kill bacteria)
Hydrolytic enzymes that are active under acidic conditions (pH is around 5 inside)

Question 17

Different pathways for lysosomes

Answer 17

Phagocytosis - one cell engulfs another
Autophagy - recycling cell organelles or macromolecules

Question 18

Peroxisomes

Answer 18

Enclosed by single membrane
Breaks down hydrogen peroxide
Not lysosomes, but oxidative
Break down H2O2
Break down fatty acids and amino acids
May detoxify poisons

Question 19

Vacuoles

Answer 19

Large vesicles derived from the ER and Golgi apparatus

Question 20

Food vacuoles

Answer 20

Formed by phagocytosis

Question 21

Contractile vacuoles

Answer 21

Pump excess water out of cell

Question 22

Central vacuole

Answer 22

Hold organic compounds and water

Question 23

Mitochondria

Answer 23

Sites of cellular respiration
Uses oxygen to generate
Found in nearly all eukaryotic cells and function in chemical energy conversion
Smooth outer membrane and inner membrane folded into cristae

Question 24

Chloroplasts

Answer 24

Found in plants and algae
Sites of photosynthesis
Capture light energy and converts to chemical bond energy
Contain chlorophyll

Question 25

Cytoskeleton

Answer 25

Network of proteins that determine shape of the cell Give cell its shape Allows cell to organize internal components Movement

Question 26

Intermediate filaments

Answer 26

Found in cytoplasm of most animal cells Have great tensile strength Toughest and most durable cytoskeletal filament Enable cels to withstand mechanical stress of stretching

Question 27

Actin (microfilaments)

Answer 27

Polymers of the protein actin Thin, flexible protein threads Present in all eukaryotic cells Essential for movement

Question 28

Microtubules

Answer 28

Long and stiff hollow tubes Rapidly disassemble in one direction and reassemble in another In animal cells, they grow across cell and create tracks to transport cell components During mitosis form mitotic spindles Form cilia and flagella

Question 29

Cilia

Answer 29

Hairlike structures found on surface of cells Can move fluid over surface by moving in unison

Question 30

Eukaryotic flagella

Answer 30

Long whip-like structure Longer version of cilia Capable of moving a cell through a fluid medium

Question 31

Plasmodesmata (plants)

Answer 31

Channels that pass between cell walls in plants to connect cytoplasm and allow materials to move from cell to cell

Question 32

Tight junctions (animals)

Answer 32

Watertight seals between animal cells that prevent materials from leaking between cells Found in epithelial cells that line internal organs and cavities

Question 33

Desmosomes (animals)

Answer 33

Short proteins in plasma membrane (cadherins) that act as spot welds Join adjacent cells in tissues that stretch

Question 34

Gap junctions

Answer 34

Form channels that allow ions, nutrients, and other materials to move between cells Develop when 6 proteins (connexins) form an elongated donut light structure (connexon) in plasma membrane When connexons of adjacent cells are aligned, it completes the channel