Chapter 3: Cell Structure And Internal Compartments

Question 1

Cell theory

Answer 1

Unifying principle of biology
Every living organism is composed of one or more cells
All cells living today came from a pre existing cell

Question 2

Plasma membrane

Answer 2

Forms barrier from its surrounding environment
Facilitate waste and nutrient exchange
Facilitates communication with other cells and the environment (structures along the membrane)

Question 3

Plasma membrane’s semi-permeability

Answer 3

Molecules that pass through without much trouble: small, non-polar/hydrophobic, water
Molecules less likely to pass through without assistance: polar molecules, large molecules, ions

Question 4

Molecules associated with cellular membrane

Answer 4

Proteins: transport, communication, adhesion, structural
Lipids: structural, communication
Carbohydrates: cell-cell direct communication, structural

Question 5

Surface area to volume ration limits cell size

Answer 5

SA:V
Forms a barrier to how long/large a cell can get
Large number = faster exchange of materials with environment
Smaller number = slower exchange of materials with environment

Question 6

Strategies to deal with SA:V limits

Answer 6

Stay small
Flatten out/create folds, but keep volume the same
Compartmentalism/duplicate functions
Go colonial/multicellular

Question 7

Colonial organisms

Answer 7

Loose group of cells that cooperate for mutual benefit - can exist independently

Question 8

Multicellular organisms

Answer 8

An interdependent group of genetically identical cells that developed from a single cell

Question 9

Organelles

Answer 9

cellular structure that performs a unique function in the cell
Often covered in at least one membrane - allows you to have more surface available to the cell

Question 10

Prokaryotic cell structure

Answer 10

Most prokaryotes have a cell wall outside the plasma membrane
No nucleus, no membranous organelles (mitochondria, chloroplasts, etc.)
Ribosomes are important for protein-manufacturing organelles - the only organelle type present in prokaryotes

Question 11

Eukaryotic cells

Answer 11

Highly structured, efficient factories that have the capacity to reproduce themselves
Complex and compartmentalizations via membrane-bound organelles
Larger than prokaryotes

Question 12

Nucleus

Answer 12

Bonded by a bobble plasma membrane called the nuclear envelope - contains nuclear pored that smallish molecules pass freely and is not permeable to larger objects
Contains DNA required for building, managing, growing, and reproducing cells
DNA may be condensed into chromosomes
DNA does not leave the nucleus

Question 13

Ribosomes

Answer 13

Only organelle that is in both prokaryotic and eukaryotic cells
Converts RNA to protein

Question 14

The Central Dogma

Answer 14

DNA&raquo_space; RNA&raquo_space; Protein
Transcription (DNA&raquo_space; RNA) in eukaryotes in the nucleus, in prokaryotes in the plasma
Translation (RNA&raquo_space; Proteins) in the cytoplasm

Question 15

Chloroplasts

Answer 15

Autotrophs/producers only
Photosynthesis*
Plants and algae use a several step process in chloroplasts to capture energy from sunlight to produce organic molecules from inorganic molecules
Can happen in prokaryotes, but in the plasma membrane
The energy in plant sugars is used directly by plants and indirectly by all organisms that eat plants

Question 16

Mitochondria

Answer 16

Used by both producers and consumers
Fuels cellular activities by extracting energy from organic biomolecules - this energy originally comes from autotrophs in the form on carbohydrates
Surrounded by 2 membranes
The folds of the inner membrane help to increase the surface area for chemical reactions
Cellular respiration happens here; the process of turning food molecules into energy (ATP)

Question 17

Endoplasmic Reticulum

Answer 17

Interconnected network of tubes and flattened sacs that produces certain lipids and proteins

1. Smooth ER produces lipids for other cellular compartments and helps break down toxic organic compounds in the cell
2. Rough ER is dotted with ribosomes and produces proteins for use both inside and outside the cell

Question 18

Golgi Apparatus

Answer 18

Directs proteins and lipids produced by the ER to their final destination either inside or outside the cell using transport vesicles
Modifies Biomolecules by adding or removing components and combines the Biomolecules types

Question 19

Transport vesicles

Answer 19

Small, spherical, membrane-enclosed sacs that move biomolecules between cellular compartments
Fuses with the membrane of the target destination in order to deliver its contents

Question 20

Lysosomes

Answer 20

Disassemble macromolecules
Enzymes (proteins) break down macromolecules and release the subunits into the cytoplasm for recycling or waste removal
Interior = highly acidic with a pH or 5
Trash cans for the call - breaks down the other biomolecules

Question 21

Vacuoles

Answer 21

Unique to plants and protists
Waste treatment: act much like lysosomes to break down biomolecules
Defense: store ions and water-soluble molecules as well as noxious compounds
Structural support: anoles filled with water provide turgor pressure, which helps make the non-woody parts of plant cells rigid
Pigmentation

Question 22

The Evolution of Eukaryotes

Answer 22

Eukaryotic organelles are believed to have originally been free-loving prokaryotes that were engulfed by a predatory cell
*Mitochondria and Chloroplasts were the basis of this belief because they contain their own DNA they have bacterial-style DNA and ribosomes, and have 2 surrounding membranes

Question 23

The number and type of organelles may vary from cell to cell

Answer 23

Chloroplasts - leaves
Mitochondria - where power is needed
Ribosomes - where more protein is needed
Smooth ER - detoxification