Cell structure, Chapter 4

Question 1

• Cells were first observed in the 17th century by?

Answer 1

Robert hooke

Question 2

Modern cell theory is based on 3 principles

Answer 2

• All organisms composed of one or more cells
• Cells are smallest living things
• Cells arise only by division of a previously existing cell

Question 3

Solutes move from a high concentration to low concentration

Answer 3

Diffusion

Question 4

Rate of diffusion is affected by

Answer 4

• surface area available for diffusion
• temperature
• concentration gradient of diffusing substance
• distance over which diffusion must occur

Question 5

Surface Area to volume ratio

Answer 5

As a cell’s size increases, its volume increases much more rapidly than its surface area
- small cells have an advantage over an larger cells

Question 6

Light microscopes

Answer 6

• Use magnifying lenses with visible light
• Can view some cells, but few cellular structures
• Limit to resolution using light

Question 7

Electron microscopes

Answer 7

• Use a beam of electrons
• Able to view cellular structures
• Transmission electrons microscopes through the material
• Scanning electron microscopes beam electrons onto the specimen surface

Question 8

Cells share simple structural features

Answer 8

• A localized area where genetic material is stored
• The cytoplasm
• All cells have ribosomes
• A plasma membrane

Question 9

Prokaryotic

Answer 9

• Bacteria and Archaea
• Simple cellular structure- an organization
• Lack of a membrane-bound nucleus
• Do not have an internal membrane system
• Huge diversity in prokaryotic metabolism, function and ecology
• Cytoplasm surrounded by a plasma membrane and encased by a cell wall
• Contain ribosomes for protein synthesis
• No membrane-bound organelles- operate as a single unit

Question 10

Bacteria cell walls

Answer 10

• Composed of Peptidoglycan, a carbohydrate matrix cross-linked with shirts polypeptide units

Question 11

some antibiotics function by disrupting the peptidoglycan layer of bacteria cells

Answer 11

killing the cells

Question 12

Cell walls

Answer 12

Protect the cell, maintain shape and prevents excess water loss/uptake

Question 13

long threadlike structures protruding from the surface of a cell, used in locomotion

Answer 13

Flagella

Question 14

Eukaryotic cells

Answer 14

• Cells are broken up into compartments through the endomembrane system and organelles allowing the simultaneous and independent biochemical processes to occur
• The nucleus acts as the information center
• Largest organelle
• The nucleus contains genetic information
• Contain a single nucleus
• Nuclear envelope; bounded by 2 phospholipid bilayer membranes
• Nuclear pores; occur across the nuclear envelop- allowing ions and small molecules to diffuse freely- transport proteins that function in the nucleus
• Nuclear envelop covered with fibers that make up the nuclear lamina
• Gives the nucleus its shape and is involved in cell division
• DNA is divided into chromosomes organized into a complex structure called chromatin
• The structure of chromatin affects the function of DNA
• Nucleolus; area of concentrated RNA synthesis and ribosome assembly within the nucleus
• To make proteins cells must first make ribosomes
• Ribosomes: complex structures and are made up of 2 subunits
• Messenger RNA(mRNA): coding information from DNA and is used to direct synthesis
• Ribosomes are either free or membrane-associated

Question 15

• The interior of the cell is packed with internal membranes
• divide cells into compartments

Answer 15

Endomembrane system

Question 16

• largest internal membrane
• phospholipid bilayer embedded with proteins
• divided into 2 subdivisions

Answer 16

Endoplasmic reticulum (ER)

Question 17

• proteins synthesized on the surface of the RER are destined to be exported from the cell, sent to lysosomes or vacuoles, or embedded in the plasma membrane
• Protein leaves the RER to be sorted to their final destination

Answer 17

The rough ER (RER) is a site of protein synthesis

Question 18

• Membranes of the SER contain many embedded enzymes, involved in the synthesis of carbohydrates and lipids
• The majority of membrane lipids are assembled in the SER
• SER stores intracellular Ca2+, used in diverse signaling pathways
• The SER modifies foreign substances to make them less toxic
• in the liver enzymes in the SER carry out detoxification

Answer 18

The Smooth ER (SER) has multiple roles

Question 19

The ratio of RER to SER in cells depend on

Answer 19

The cells function

Question 20

• Sorts and packages proteins
• complex flattened stacks of membranes
• size and # of cistern varies across organism and cell types
• Abundant in cells that manufacture and secrete proteins

Answer 20

Golgi apparatus

Question 21

• located near ER
• ## proteins arrive in transport vesicle that bud off ER

Answer 21

Cis face

Question 22

• proteins exit and are discharged in secretory vesicles

Answer 22

Trans face

Question 23

Add short sugar chains
- Glycoproteins or glycolipids

Answer 23

Glycosylation

Question 24

• digestive vesicles that arise from the GA
• contain many enzymes to degrade macromolecules
• break down old organelles and recycle their molecules
• have optimal activity at an acid pH
• conditions could kill cell=keep compartmentalized
• activated by fusing with what they will breakdown
• fission activates proton pumps
• pump H+ in and lowers pH- activating digestive enzymes

Answer 24

Lysosomes

Question 25

Tay-Sachs disease

Answer 25

• caused by the loss of function of a single lysosomal enzyme
• necessary to breakdown membranes glycolipid found in nerve cells
• leads to seizures and muscle rigidity

Question 26

Organelles consisting of a neutral lipid core, surrounded by a single layer of phospholipid

Answer 26

lipid droplets