Sub-Cellular Structures: Eukaryotic Cell

Question 1

What are the sub-cellular structures? (7)

Answer 1

Nucleus
Endoplasmic Reticulum
Golgi Apparatus
Lysosome
Mitochondria
Ribosomes
Centrioles

Question 2

The structures within the nucleus? (5)

Answer 2

the nuclear envelope, nuclear pores, nucleoplasm, chromosomes, nucleolus

Question 3

What is the nucleus’s structure and function?

Answer 3

structure: largest organelles, spherical, dark patches= chromatin, nuclear envelope surrounds, two fluid-filled membranes, nuclear pores, allows large molecules through, nucleolus inside
function: genetic material, chromatin consists of DNA and proteins, contains instructions for making proteins, chromatin condenses when cell division occurs into visible chromosomes, nucleolus makes mRNA and tRNA and ribosomal RNA and ribosomes

Question 4

What is the nuclear envelope?

Answer 4

a double membrane that surrounds the nucleus, its outer membrane is continuous with the endoplasmic reticulum of the cell, often has ribosomes on its surface, controls entry and exit of material and contains the reactions taking place

Question 5

What do the pores do?

Answer 5

they allow the passage of large molecules e.g. messenger RNA out of the nucleus. around 3,000 pores in each nucleus 40-100mm in diameter

Question 6

What is the nucleoplasm?

Answer 6

it is the granular, jelly-like material that makes up the bulk of the nuclues

Question 7

What do chromosomes consist of?

Answer 7

protein bound, linear DNA

Question 8

What is the nucleolus?

Answer 8

is a small spherical region within the nucleoplasm. it manufactures ribosomal RNA and assembles the ribosomes

Question 9

What is the endoplasmic reticulum’s structure and function?

Answer 9

structure: consists of flattened membrane-bound sacs - cisternae which are continuous with the outer nuclear membrane, rough ER ribosomes, smooth ER no ribosomes
function: smooth ER is included in making lipids, rough ER transports proteins made on attached ribosomes

Question 10

What are the functions of the rough and smooth ER?

Answer 10

rough ER: provide a large surface area for the synthesis of proteins and glycoproteins, provides a pathway for the transport of materials especially proteins
smooth ER: synthesise store and transport lipids and synthesise store and transport carbohydrates

Question 11

What is the Golgi apparatus’s structure and function?

Answer 11

structure: stack of membrane-bound, flattened sacs
function: receives proteins from the ER, packages proteins into vesicles to be transported inside the cell or outside, add carbohydrates to proteins to form glycoproteins, produces secretory enzymes, secrete carbohydrates, transport modify and store lipids, form lysosomes

Question 12

What is the lysosome’s structure and function?

Answer 12

structure: spherical sacs surrounded by a single membrane
function: contains digestive enzymes which break down material, they hydrolyse material ingested by phagocytic cells e.g. WBC, releases enzymes to the outside cell (exocytosis) in order to destroy material around the cell, digest worn out organelles so that the usefull chemcials that made them up can be re-used, completely break down cells after they have died (autolysis)

Question 13

What is the mitochondria’s structure and function?

Answer 13

structure: two membranes separated by a fluid-filled space the inner membrane is folded to form cristae central part of the matrix, provides a large surface area for the attachment of enzymes and other proteins involved in respiration, the matrix is the main bulk and contains protein, lipids, ribosomes, and DNA that allows mitochondria to control the production of some of their own proteins
function: site where ATP is produced during respiration

Question 14

What are ribosome’s structure and function?

Answer 14

structure: very small organelles in the cytoplasm and bound to rough ER, consists of two sub-units
function: site of protein synthesis which acts as an assembly line to use mRNA to assemble proteins

Question 15

What are centrioles’ structure and function?

Answer 15

structure: small protein tubes of microtubules
function: form fibres in cell division known as spindles which separate chromosomes

Question 16

What are the structures and functions of the chloroplast?

Answer 16

Structure: The chloroplast envelope is a double plasma membrane that surrounds the organelle. It’s highly selective in what it allows in and out. The grana are stacks of up to 100 disk-like structures called thylakoids within the thylakoids, which is the photosynthetic pigment called chlorophyll. The grana are where the light absorbtion takes place. The stroma is a fluid filled matrix white. The synthesis of sugars takes place within the stroma are structures e.g. starch grains
Function: the granal provide a large surface area for attachment of chlorophyll electron carriers and enzymes that carry out the light absorbtion. These chemicals are attached to the membrane. The fluid og the stroma possesses all the enzymes needed to make sugars for the synthesis of sugars. Chloroplast contain both DNA and ribosomes so they can quickly and easily manufacture some of the proteins needed for photosynthesis

Question 17

What are the structures and functions of the cell wall?

Answer 17

Structure: they consist of a number of polysacchorides such as cellulose. There is a thin layer called the middle lamella, which marks the boundary between adjacent cell walls and cement adjacent cells together
Functions: to provide mechanical strength in order to prevent the cell bursting under the pressure created by the osmotic entry of water. To give mechanical strength to the plant as a whole. To allow water to pass along it and so contribute to the movement of water through the plant

Question 18

What are the structures and functions of the vacuole?

Answer 18

Structure: The single membrane around it is called the tonoplast. A plant vacuole contains a solution of mineral salts, sugars, amino acids, wastes, and sometimes pigments such as anthocychins.
Function: They support herbaceous plants and herbaceous plants of woody plants by making the cells turgid. The sugars and amino acids may act as a temporary food store. The pigments may colour petals to attract pollinating insects