Cell structure

Question 1

Illustrate the cell theory by Schleiden and Schwann

Answer 1

-Cells are the basic structural and physiological units of all organisms. -Cells are both distinct entities and buildin blocks of more complex organisms.

Question 2

What are the two important implications of the cell theory?

Answer 2

1) Studying cell biology is the same as studying life. 2) Life is continuous: all cells in our body come from a single cell.

Question 3

Why are cells small?

Answer 3

Small cell size is a practical necessity arising from the change in the surface area-to-volume ratio.

Question 4

What are the key features of ALL prokaryotic cell?

Answer 4

1- A plasma membrane 2- A nucleoid 3- Cytoplasm

Question 5

What is the nucleoid in prokaryotic cells?

Answer 5

The region where DNA is located.

Question 6

What are the two main components of prokaryotic cytoplasm?

Answer 6

1) Water that contains ions, small molecules and solube macromolecules. 2) Ribosomes.

Question 7

What are the features found in SOME prokaryotic cells?

Answer 7

1) Cell wall 2) Internal membrane 3) Flagella 4) Fimbriae and pili 5) Cytoskeleton

Question 8

Describe the cell wall of the prokaryotic cells:

Answer 8

A robust layer outside the plasma membrane providing structural integrity and protection.

Question 9

Describe flagella in prokaryotic cells:

Answer 9

A complex motor protein spins a flagellum made of flagellin on its axis like a propeller.

Question 10

Describe fimbriae and pili in prokaryotic cells:

Answer 10

Hairlike structure used for adherence and movement.

Question 11

State the two most important differences between the eukaryotic and prokaryotic cells:

Answer 11

-Eukaryotic are larger and prokaryotic cells -Eukaryotic cell contain membrane-bound organelles

Question 12

What are the two roles of the membrane sorrounding the organelles in the eukaryotic cells?

Answer 12

1) Keeps the organelle’s molecules away from other molecules in the cell, to prevent inappropriate reactions. 2) Act as a traffic regulator, letting important raw material into the organelle

Question 13

Describe the nucleus

Answer 13

The nucleus contains most of the cell genetic material.

Question 14

Describe the mitchondrion

Answer 14

Is where the energy stored in the bonds of carbohydrates and fatty acid is converted into a useful form for the cell.

Question 15

Describe the overall function of the endoplasmic reticulum and the golgi apparatus:

Answer 15

Are compartments in which cells in synthesize some proteins.

Question 16

Describe the overall function of lysosome and vacuole:

Answer 16

Cellular digestive systems in which large molecules are hydrolyzed into usable monomers.

Question 17

What are the three different places where you can find robosomes?

Answer 17

1- Free in the cytoplasm 2- Attached to endoplasmic reticulum 3- Inside the mitochondria and chloroplast

Question 18

State all the characteristics of the nucleus:

Answer 18

-It contains the chromosomes -It is bounded by the nuclear envelope. -Is the location od DNA replication and transcription.

Question 19

What is the nuclear envelope?

Answer 19

Is a double membrane that separates the DNA from the cytoplasm.

Question 20

What is the only way for macromolecules to enter or exit the nucleus?

Answer 20

Through nuclear pores located on the nuclear envelope.

Question 21

What are the 5 components of the endomembrane system?

Answer 21

1) The plasma membrane 2) Nuclear envelope 3) Endoplasmic reticulum 4) Golgi Apparatus 5) Lysosomes and vacuoles.

Question 22

Describe the endoplasmic reticulum:

Answer 22

Is the totality of all membrane branching throughout the cytoplasm, forming tubes and flattened sacs. Is differentiated into rough endoplasmi reticulum and smooth endoplasmic reticulum.

Question 23

Describe the rough endoplasmic reticulum:

Answer 23

Is called rough because of the many ribosomes attached to it. It receivse newly synhtesized proteins, segregating them away from the cytoplasm and transport them in other locations.

Question 24

Describe the smooth endoplasmic reticulum:

Answer 24

It lacks ribosomes and is more tubular than the RER. It’s responsable for the chemical modification of small molecules taken by the cell and the site of glycogen degradation and synthesis in animal cells.

Question 25

What are the two components of the Golgi apparatus

Answer 25

1) Cisternae 2) Small-membrane enclosed veiscles.

Question 26

Describe the cisternae also stating the three regions that compose them:

Answer 26

Flattened membranous sacs called cisternae: 1) Cis region lies nearest to the nucles or a patch of RER. 2) Trans region lies nearest to the plasma membrane. 3) Medial region lies in between.

Question 27

Describe the lysosomes:

Answer 27

Lysosomes conain digestive enzymes and they are site where macromolecules are hydrolyzed into their monomers.

Question 28

State and describe the two different membranes of the mitochondria:

Answer 28

-Outer membrane: small and protective and not really selective. -Inner membrane: much more selective and contains proteins that participate in cellular respiration.

Question 29

What is the mitochondrial matrix?

Answer 29

Is the space enclosed by the inner membrane of the mitochondrion.

Question 30

Describe the features of the chloroplasts:

Answer 30

They contain the green photopigment chlorophyll and are the sites of photosynthesis.

Question 31

What are the five functions of vacuoles:

Answer 31

1) Storage 2) Structure 3) Reproduction 4) Digestion 5) Contractile vacuoles.

Question 32

What are the roles of the cytoskeleton?

Answer 32

It support the cell and help it maintains its shape. It holds organeless in their position or move them. It interacts with the extracellular structures, helping anchor the cell in place.

Question 33

Describe the roles of microfilaments:

Answer 33

1) Allow the cell or part of it to move. 2) Determine and stabilize the cell shape. They are assembled by actin monomers.

Question 34

Describe the roles of intermediate filaments:

Answer 34

1) They anchro the cell structure in place. 2) They help resisting tension.

Question 35

Describe microtubules:

Answer 35

The large diameter components of the cytoskeleton. 1) They form a rigid internal skeleton. 2) They act as a framework along which moto proteins can move.

Question 36

Describe the function of dynein:

Answer 36

Motion of cilia and flagella results from the sliding of the microtubules doublets past each other and this movement is driven by dynein.

Question 37

Describe the function of nexin:

Answer 37

It can cross-link the doublets and prevent from moving and sliding, in this case the cilium bends.

Question 38

Describe kinesin:

Answer 38

It carries protein laden vesicles from one part to another walking along a microtubule by a repeated series of shape changes.

Question 39

What are the two main components of extracellular structures in general:

Answer 39

1) A prominent fibrous molecule. 2) A gel like medium in which fibres are embedded.

Question 40

Describe the plant cell wall and its major roles:

Answer 40

Is a semirigd structure outside the plasma membrane with 3 major roles: 1) It provides support for the cell and limits its volume by remaining rigid- 2) It acts as a barrier to infection of fungi and other disease causing microorganisms. 3) It contributes to plant form by growing as plant cells grow.

Question 41

What are the two components of the extracellular matrix:

Answer 41

1) A fibrous protein called collagen. 2) A matrix of glycroproteins.

Question 42

What are the 5 functions of the extracellular matrix:

Answer 42

1) Holds the cell tissue in position. 2) It contributes to the physical properties of cartilage. 3) It helps filter materials passing between different tissues. 4) It helps orienting the cell movements during embryonic development. 5) It plays a rle in chemical signalling between cells.