Eukaryotic cell structure

Question 1

What is a Eukaryote?

Answer 1

A Eukaryote is any organism consisting of one or more cells that contain DNA in a membrane bound nucleus- separate from the cytoplasm.

Question 2

What are the 4 types of Eukaryote?

Answer 2

Animals, plants, fungi, protists.

Question 3

How can we look at organelles within a cell?

Answer 3

We need to use an electron microscope.

Question 4

What is the purpose of a lysosome?

Answer 4

Lysosomes hold enzymes that were created by the cell. The purpose of the lysosome is to digest things. They might be used to break down the cell when it dies.

Question 5

What is the purpose of ribosomes?

Answer 5

Ribosomes are the protein synthesizers of the cell.

Question 6

What is the purpose of the cell wall?

Answer 6

To provide mechanical strength in order to prevent the cell bursting under the pressure created by osmotic entry of water. And to allow water to pass along it to contribute to the movement of the water through the plant.

Question 7

What is the function of a vacuole?

Answer 7

They support plants by making the cells turgid. A drooping plant has lost much of its water and the vacuoles are shrinking.

Question 8

What is the function of the nucleus?

Answer 8

It’s the control centre through the production of mRNA and tRNA. They retain the genetic material of the cell in the form of DNA.

Question 9

What is the function of the mitochondrion?

Answer 9

Mitochondria are tiny structures found in cells (one is called a mitochondrion). Respiration, the chemical reaction that releases energy from glucose, happens in mitochondria. This provides energy for life process such as movement and growth.

Question 10

What is the function of chloroplasts?

Answer 10

Chloroplasts are the tiny structures in plant cells where photosynthesis happens. Chloroplasts contain chlorophyll, a green pigment that absorbs light energy for photosynthesis.

Question 11

What is the difference between RER and SER?

Answer 11

Rough ER (RER) is involved in some protein production, protein folding, quality control and despatch. It is called ‘rough’ because it is studded with ribosomes

Smooth E R (SER) is associated with the production and metabolism of fats and steroid hormones. It is ‘smooth’ because it is not studded with ribosomes and is associated with smooth slippery fats.

Question 12

What do RER and SER stand for?

Answer 12

Rough/soft endoplasmic reticulum

Question 13

How do you identify the Golgi apparatus?

Answer 13

They’re flattened disc-like structures located close to the endoplasmic reticulum.

Question 14

What is the funcion of the Golgi apparatus?

Answer 14

The Golgi apparatus receives proteins and lipids (fats) from the rough endoplasmic reticulum. It modifies some of them and sorts, concentrates and packs them into sealed droplets called vesicles. Depending on the contents these are despatched to one of three destinations:

Destination 1: within the cell, to organelles called lysosomes.
Destination 2: the plasma membrane of the cell
Destination 3: outside of the cell.

Question 15

What’s an ultrastructure?

Answer 15

When a cell has an internal structure that is suited for its function.

Question 16

What is the nucleus made up of?

Answer 16

The nuclear envelope, nuclear pores, nucleoplasm, chromosomes, nucleolus.

Question 17

What’s the nuclear envelope?

Answer 17

A double membrane that surrounds the nucleus. The outer membrane is continuous with the ER of the cell and often has ribosomes on its surface. It controls the entry and exit of materials in and out of the nucleus and contains the reactions taking place in it.

Question 18

What are the nuclear pores?

Answer 18

Pores that allow the passage of large molecules out of the nucleus.

Question 19

What is the nucleoplasm?

Answer 19

The granular, jelly-like material that makes up the bulk of the nucleus.

Question 20

What is the nucleolus?

Answer 20

A small spherical region within the nucleoplasm that manufactures ribosomal RNA and assembles the ribosomes.

Question 21

What are chromosomes?

Answer 21

They are protein-bound, linear DNA

Question 22

What are the functions of the nucleus?

Answer 22

• To act as a control centre of the cell through the production of mRNA and tRNA and hence protein synthesis.
• To retain the genetic material of the cell in the form of DNA and chromosomes
• To manufacture ribosomal RNA and ribosomes.

Question 23

What do mitochondrion look like?

Answer 23

They are usually rod-shaped and 1-10 lu m in length.

Question 24

What does the double membrane do on a mitochondrion?

Answer 24

It controls the entry and exit of material. The inner of the two membranes is folder to form extensions known as cristae.

Question 25

What are cristae?

Answer 25

They are extensions of the inner membrane, these provide a large surface area for the attachment of enzymes and other proteins involved in respiration.

Question 26

What is the matrix in the mitochondrion?

Answer 26

It contains protein, lipids, ribosomes and DNA that allows the mitochondria to control the production of some of their own properties. Many enzymes involved in respiration are found here.

Question 27

Mitochondria are responsible for the production of which energy- carrier molecule?

Answer 27

ATP (from substances such as glucose).

Question 28

What is the chloroplast envelope?

Answer 28

A double plasma membrane that surrounds the organelle. It is highly selective in what it allows to enter and leave the chloroplast.

Question 29

What are grana?

Answer 29

Stacks of disc-like structures called THYLAKOIDS. Within the thylakoids is the photosynthetic pigment called chlorophyll. Some thylakoids have tubular extensions that join up with thylakoids in adjacent grana. This is where light absorption takes place.

Question 30

What is the stroma in chloroplasts?

Answer 30

A fluid-filled matrix where the second stage of photosynthesis takes place. Within the storms are a number of other structures such as starch grains.

Question 31

How are chloroplasts adapted to their function?

Answer 31

• Granal membranes provide a large surface area for the attachment of chlorophyll, electron carriers and enzymes that carry out the first stage of photosynthesis. These chemicals are attached to the membrane in a highly ordered fashion.
• The fluid of the stroma possesses all the enzymes needed to make sugars in the second stage of photosynthesis.
• Chloroplasts contain both DNA and ribosomes so they can quickly and easily manufacture some of the proteins needed for photosynthesis.

Question 32

What is the endiplasmic reticulum?

Answer 32

It’s an elaborate, 3ad system of sheet-like membranes, spreading through the cytoplasm of the cells. It is continuous with the outer nuclear membrane. The membranes enclose a network of tubules and flattened sacs called custernae.

Question 33

What is the function of the ribosomes on the RER?

Answer 33

• Provide a large surface area for the synthesis of the proteins and glycoproteins
• Provide a pathway for the transport of materials, especially proteins, throughout the cell.

Question 34

Functions of SER?

Answer 34

• synthesise, store and transport lipids

- synthesise, store and transport carbohydrates.

Question 35

Cells that manufacture and store large quantities of carbohydrates, proteins and lipids have a very extensive, what?

Answer 35

ER, such cells include the liver and secretory cells, for example the epithelial cells that line the intestine.

Question 36

What does the Golgi apparatus consist of?

Answer 36

A stack of membranes that make up flattened sacs, or cisternae, with small rounded hollow structures called vesicles.

Question 37

What does the Golgi apparatus do?

Answer 37

It modifies proteins often adding non-protein components, such as carbohydrate, it also ‘labels’ them allowing them to be accurately sorted and sent to the correct destination.

Question 38

How do the Golgi vesicles work?

Answer 38

They transport the proteins and lipids, they are pinched off from the end of the Golgi cisternae. These vesicles may move to the cell surface, where they fuse with the membrane and release their contents to the outside.

Question 39

What are the functions of the Golgi apparatus?

Answer 39

• Add carbohydrate to proteins to form glycoproteins
• Produce secretory enzymes, such as those secreted by the pancreas
• Secrete carbohydrates, such as those used in making cell walls in plants
• Transport, modify and store lipids
• Form lysosomes

Question 40

How are lysosomes formed?

Answer 40

When the vesicles produced by the Golgi apparatus contain enzymes such as proteases and lipases. They also contain lysozomes, enzymes and hydrolyse and the cell walls of certain bacteria. Lysosomes isolate these enzymes from the rest of the cell before releasing them into a phagocytic vesicles or outside.

Question 41

Where are 80s and 70s ribosomes found?

Answer 41

80s- eukaryotic cells

70s- prokaryotic cells, mitochondria and chloroplasts, is slightly smaller.

Question 42

What does a cell wall consist of?

Answer 42

Microfibrils of the polysaccharide cellulose, embedded in a matrix. The cellulose microfibrils have considerable strength and so contribute to overall strength.

Question 43

What features does a cell wall have?

Answer 43

• They consist of a number of polysaccharides, such as cellulose.
• There is a thin layer, called the middle lamella, which marks the boundary between adjacent cell walls and cements adjacent cells together.