Cell Structures + Functions

Question 1

What are the main similarities between prokaryotic and eukaryotic cells?

Answer 1

• All cells are bound by a cellular membrane (plasma membrane)
• All cells contain cytosol, a jelly-like fluid in which all the cell’s components are suspended within
• All cells contain chromosomes
• All cells have ribosomes which make proteins

Question 2

What is the major difference between prokaryotic and eukaryotic cells?

Answer 2

The main difference between prokaryotic and eukaryotic cells is the location in which they contain their DNA

Prokaryotic cells contain their DNA in a small region of the cell which is not enclosed by any membrane, referred to as the nucleoid

Eukaryotic cells contain their DNA within an organelle known as the nucleus, a double membrane-bound structure

Question 3

what are some common differences between prokaryotic and eukaryotic cells?

Answer 3

• Eukaryotic cells consist of membrane-bound organelles, all of which are not found in prokaryotic cells
• Eukaryotic cells tend to be much larger than prokaryotic cells

Question 4

How do metabolic requirements set a limit on cell size?

Answer 4

A cell’s size greatly reflects the cell’s capability to meet its metabolic requirements for survival.

The plasma membrane which is known to be a semi-permeable barrier may only allow a certain amount of substance to cross per second and therefore with a greater volume, comes greater metabolic requirements which the small surface area of the cell may not be able to provide for.

Question 5

Define the term nuclear envelope.

Answer 5

The double membrane is a lipid bilayer which encloses nucleic acids within.

Question 6

What does the nuclear lamina do for the nucleus?

Answer 6

The nuclear lamina is a lining found on the nuclear side of the nucleus made up of a net-like array of protein filaments which maintains the shape of the nucleus and provide mechanical support to the nuclear envelope

Question 7

What role does the nuclear pore complex play in the cell?

Answer 7

The pore complex is a protein structure which ranges the entire nuclear envelope. these pores play a large role in the regulation of entering and exiting proteins and RNA

Question 8

Where in the nucleus is ribosomal RNA synthesized?

Answer 8

Ribosomal RNA is synthesized within the nucleolus, a structure within the nucleus composed of a compact arrangement of densely stained granules using genes from DNA

Question 9

What is the nucleolus responsible for?

Answer 9

The nucleolus is responsible for synthesizing ribosomal RNA using genes present in DNA and also plays a role in controlling cell division

Question 10

How does the nucleus direct protein synthesis?

Answer 10

The nucleus synthesizes mRNA (messenger RNA) which carries instructions for protein synthesis from the DNA into the cytoplasm where ribosomes will translate the mRNA into the primary structure of polypeptide.

Question 10

How are ribosomes assembled after synthesis?

Answer 10

After synthesis in the nucleolus, rRNA is then grouped with proteins imported from the cytosol making up large and small ribsome subunits. The subunits then exit the nucleus through its nuclear pores, in the cytosol, the small and large subunits assemble to make up ribosomes

Question 10

What are the major components which make up ribosomes?

Answer 10

Ribosomes are made up of small and large subunits of rRNA and proteins which are assembled in the cytosol after synthesis inside the nucleolus

Question 11

What is the major function of ribosomes?

Answer 11

Ribosomes are known as protein factories for their main function is to carry out protein synthesis through mRNA, tRNA

Question 12

What does it mean for a cell to have a large number of ribosomes?

Answer 12

This means that the cell undergoes high rates of protein synthesis

Question 13

What is the difference between free and bound ribosomes?

Answer 13

While free ribosomes are found suspended in the cytosol, bound ribosomes are found attached to the outer surface of the endoplasmic reticulum or the nuclear envelope. Function-wise, either or can play both roles but free ribosomes generally produce more proteins which are beneficial within the cytosol such as enzymes whereas proteins produced by bound ribosomes are meant to enter the the membranes of the organelles they are bound to.

Question 14

What cell structures make up the endomembrane system?

Answer 14

The structures which make up the endomembrane system include:
- the plasma membrane
- the nucleus
- the endoplasmic reticulum
- the Golgi apparatus
- lysosomes
- different vesicles and vacuoles.

Question 15

What are the three major functions of the endomembrane system?

Answer 15

1) Protein Synthesis and Transport in and out of the cell
2) Metabolism
3) Detoxification

Question 16

How are all the different membranes of the endomembrane system relative and different from one another?

Answer 16

Though each membrane within the endomembrane is responsible for different functions and consists of different shapes and sizes, each membrane is either physically connected or through the transport of segments through membranes

Question 17

Which region of the ER’s membrane is continuous with the nuclear envelope? What is evidence of this?

Answer 17

The nuclear envelope is continuous with the rough ER given that the nuclear membrane and the outer membrane of the rough ER consist of a series of attached ribosomes.

Question 18

Why are the two regions of the ER called “rough” and “smooth” ER

Answer 18

Rough ER - covered in ribosomes making the outer membrane seem rough

Smooth ER - does not consist of ribosomes attached to it’s outer membrane

Question 19

What are some of the main functions of the smooth ER?

Answer 19

Some of the main functions of the smooth ER include:
- detoxification
- synthesizing lipids
- the metabolism of carbohydrates
-storing calcium ions

Question 20

What are some of the main functions of the rough ER?

Answer 20

Some of the major functions of the rough ER include
- the formation of proteins
- membrane growth

Question 21

Why is the rough ER known as a membrane factory for the cell?

Answer 21

This is because the rough ER is known to consistently aid its membrane’s growth by directing proteins made by ribosomes attached to its surface to the growth of its membrane along with phospholipids imported from the cytosol membrane while also transporting segments of the synthesized membrane through vesicles to other parts of the endomembrane system

Question 22

What’s known as the shipping and receiving center of the endomembrane system? Why?

Answer 22

The Golgi apparatus is known as the shipping and receiving center of the endomembrane system because this is where vesicles carrying proteins or even waste products from the rough ER are modified, stored and sent to other parts of the cell.

Question 23

What are the two sides of the Golgi apparatus's cisternae? What are they both responsible for?

Answer 23

The two sides of the Golgi apparatus include the cis face and the trans face cis face - the cis face of the Golgi's cisternae is in charge of receiving products transported from rough ER trans face - the trans face of the Golgi's cisternae is in charge of shipping products to their destinations

Question 24

When does modification of products take place in the Golgi apparatus?

Answer 24

The modification of products in the Golgi apparatus takes place when moving from its cis to trans face

Question 25

What is the major function of lysosomes?

Answer 25

The major function of lysosomes is to break down and digest macromolecules

Question 26

What may excessive leaking in the lysosome result in?

Answer 26

Excessive leaking in the lysosome may cause self-digestion of the cell and ultimately death

Question 27

What are the 2 main functions of the lysosome and how do they work?

Answer 27

1) to perform intercellular digestion. More specifically phagocytosis is the process in which the cell engulfs smaller organisms creating a food vacuole which fuses with the lysosome to allow for digestion. 2) autophagy, the process in which the cell recycles its organic material with the help of lysosomes. Lysosomes fuse with the membrane of vesicles which form surrounding the damaged structure and dismantle the membrane allowing the enclosed materials to be released into the cytosol to be reused

Question 28

What is the difference between vacuoles and vesicles/

Answer 28

Vesicles are small membrane-bound enclosures which transport materials from and to the Golgi apparatus and other structures whereas vacuoles are very similar yet they are larger and their membranes are more selective than those of vesicles. While the solution inside the vesicle may remain the same as that of the cytosol, within a vacuole the solution is known to be different.

Question 29

Describe an overview of how all the structures of the endomembrane system work together

Answer 29

1) The Nucleus - contains nucliec acids - synthesizes ribosomal RNA which form large and small subunits and form ribsomes in the cytosol - synthesizes messenger RNA which carry instruction from the DNA inside the nucleus to ribsomes in the cytosol to direct the production of polypeptide chains 2) Smooth ER - detoxification - synthesizing lipids - storing calcium ions 3) Rough ER - covered in ribsomes - where proteins are formed and take their shape - membrane growth 4) Golgi apparatus - packing and shipping center - organize, store and modify proteins as per where they're needed in the cell - Products enter the golgi through the cis face and exit through the trans face 5) lysosomes - intercellular digestion - phagocytosis (cell eating) - autophagy (cell recycling) 6) vesicles + vacuoles - transporting materials from one structure to the next - fusing with lysosomes

Question 30

How are mitochondrion and chloroplast similar?

Answer 30

- Mitochondrions synthesize energy for the organism using oxygen (cellular respiration) - chloroplast converts light energy into chemical energy to be used by plants and algae (photosynthesis) - both share similar evolutionary pasts (endosymbiotic theory) In which both are said to have been prokaryotic cells which were engulfed by ancestor eukaryotic cells in which the cells formed a relationship and merged to become one - mitochondria and chloroplast are both surrounded by double membranes, proof of them once being their prokaryotic cells - both have circular DNA like prokaryotes do

Question 31

Define the specifics of the mitochondria's composition and its function

Answer 31

- made up of two membranes - contain inner membrane space in which steps of cellular respiration take place - inside consists of an inner membrane matrix - Large folds called cristae make up most of the mitochondrion and increase the overall surface area for cellular respiration to take place more efficiently - This organelle is known as the powerhouse of the cell - in charge of synthesizing ATP, carrying out a large part of cellular respiration

Question 32

Define the composition of chloroplasts and its function

Answer 32

- contain chlorophyll (green pigment) - double membrane - made up of thylakoids (flat pancakes stacked like pocket chips) - a stack is called a granum - stroma is the fluid found outside of the thylakoids - photosynthesis

Question 33

What are some functions of the peroxisome?

Answer 33

- detoxify alcohol in the liver - break down fatty acids using oxygen to be used in the mitochondria during cellular respiration - converting hydrogen peroxide into water - produce hydrogen peroxide

Question 34

What allows organelles and structures within the cell to maintain their structure and position

Answer 34

The cytoskeleton of the cell is responsible for holding organelles in place by providing mechanical support and also maintaining their shape

Question 35

What is cell motility?

Answer 35

How different organelles and structures within the cell travel from destination to destination Done with the help of the cytoskeleton and motor proteins which act as a trail and feet to walk with