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A-Level Bio > 3.4 - Eukaryotic cell structure. > Flashcards

3.4 - Eukaryotic cell structure. Flashcards

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1
Q

What are Eukaryotic Cells?

A

Eukaryotic cells include animal,plant and fungal cells

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2
Q

What is the nucleus?

A

Nucleus is the most prominent feature of a cell. The nucleus contains hereditary material of organism and controls cells activities.

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3
Q

What is the nuclear envelope?

A

Nuclear envelope is a double membrane that surrounds nucleus. The outer membrane is continuous with the ER and has ribosomes on its surface - controls entry and exit of materials in and out.

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4
Q

What are nuclear pores?

A

Allow Passage of large molecules such as messenger RNA, out of the nucleus.
- 3000 pores 40-100nm in diameter

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5
Q

What is Nucleoplasm?

A

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

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6
Q

What are chromosomes?

A

Chromosomes consist of protein-bound, linear DNA.

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7
Q

What is the Nucleolus?

A

Small spherical region in the nucleoplasm. It manufactures rRNA and assembles the ribosomes. There may be more than one nucleolus.

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8
Q

Give 3 functions of the nucleus.

A
  1. ) act as the control centre of the cell through the production of mRNA and tRNA and hence protein synthesis.
  2. ) retain the genetic material of the cell in the form of DNA and chromosomes
  3. ) manufacture ribosomal RNA and ribosomes.
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9
Q

What are mitochondria?

A

Usually rod shaped and 1-10um in length. Carry out aerobic respiration to produce ATP.

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10
Q

What is the role of the mitochondrion double membrane?

A

Controls the entry and exit of material. The inner of the two membranes is folded to form extensions known as cristae.

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11
Q

What are cristae and what are its roles?

A

Cristae are extensions of the inner membrane, which in some species extend across the whole width of the mitochondria. Provide a large surface for the attachment of enzymes and other proteins involved in respiration.

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12
Q

What is the matrix of a mitochondrion?

A

The matrix makes up the remainder of a mitochondrion. It contains proteins,lipids, ribosomes and DNA that allows mitochondria to control the production of some of their own proteins. Many enzymes involved in respiration are found in the matrix.

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13
Q

Site of aerobic respiration (Kreb’s Cycle)?

A

Mitochondria

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14
Q

What are mitochondria responsible for?

A

Aerobic respiration- responsible for the production of energy carrier molecule ATP, from respiratory substances such as glucose.

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15
Q

Why do epithelial cells contain lots of mitochondria?

A

Epithelial cells in the intestines require a lot of ATP in the process process of absorbing substances from the intestines by active transport

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16
Q

What are chloroplasts?

A

Organelles that vary in shape and size. 2-10um long and 1um in diameter. They carry out photosynthesis.

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17
Q

Role of the Chloroplast envelope

A

Double Plasma membrane that surrounds the organelle. (Highly selective)

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18
Q

What are the grana?

A

Stacks of up to 100 disc-like structures called thylakoids.

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19
Q

What are the role of thylakoids?

A

Within the thylakoids is the photosynthesis pigment chlorophyll. Some thylakoids have tubular extensions that join with thylakoids in adjacent grana.

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20
Q

What is the stroma?

A

Fluid filled matrix where the second stage of photosynthesis takes place.
Within the stroma are a number of other structures such as startch grains.

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21
Q

How are Chloroplasts adapted to their function?

A
  1. ) granal membranes
  2. ) fluid of stroma
  3. ) genetic material
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22
Q

How are granal membranes of chloroplasts adapted to their function?

A

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.

23
Q

How is the stroma adapted to its function in the chloroplasts?

A

The fluid of the stroma possesses all the enzymes needed to make sugars in the second stage of photosynthesis.

24
Q

How are chloroplasts adapted to quickly manufacture proteins needed for photosynthesis?

A

Chloroplasts contain both DNA and ribosomes so they can quickly and easily manufacture some of the protein is needed for photosynthesis.

25
Q

What is the endoplasmic reticulum?

A

The endoplasmic reticulum Is an elaborate, three dimensional 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 cisternae.

26
Q

What are the two types of endoplasmic reticulum?

A
  1. ) rough endoplasmic reticulum

2. ) smooth endoplasmic reticulum

27
Q

What is the rough endoplasmic reticulum?

A

The rough endoplasmic reticulum has ribosomes present on the outer surfaces of the membranes.

28
Q

What is the smooth endoplasmic reticulum?

A

The smooth endoplasmic reticulum lacks ribosomes on its surface and is often more tubular in appearance.

29
Q

What are the functions of the rough endoplasmic reticulum?

A

To provide a large surface area for the synthesis of proteins and glycoproteins.

Provide a pathway for the transport of materials, especially proteins, throughout the cell.

30
Q

What are the functions of the smooth endoplasmic reticulum?

A

Synthesise, store and transport lipids.

Synthesise, store and transport carbohydrates.

31
Q

What is the Golgi apparatus?

A

The Golgi apparatus occurs in almost all eukaryotic cells and is similar to the SER in structure except that it is more compact. It consists of a stack of membranes that Make up flattened sacks, or cisternae, With small rounded hollow structures called vesicles.

32
Q

What happens to proteins produced by the endoplasmic reticulum?

A

The proteins and the lipids produced by the endoplasmic reticulum are passed through the golgi apparatus in strict sequence.

The Golgi modifies these proteins often Adding non protein components, such as carbohydrate, to them.

33
Q

What are the functions of the Golgi apparatus?

A

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.

From lysosomes.

34
Q

What are lysosomes?

A

Lysosomes are formed when the vesicles was used by the Golgi apparatus contain enzymes such as proteases and lipases.

They also contain lysozymes, enzymes that hydrolyse cell walls of certain bacteria.

35
Q

How many enzymes can be contained in a single lysosome?

A

As many as 50 such enzymes may be contained in a single lysosome.

36
Q

What are functions of lysosomes?

A

Hydrolyse material ingested by phagocytic cells, (such as white blood cells and bacteria).

Release enzymes to the outside of the cell (exocytosis) in order to destroy material Around the cell.

Digest worn out organelles so that useful chemicals they are made of can be reused.

Completely break down cells after they have died.

37
Q

Where are lysosomes most abundant? (More likely to be found)

A

Given the roles that lysosomes perform, it is not surprising that they are especially abundant in secretory cells, such as epithelial cells, and in phagocytosing cells.

38
Q

What are ribosomes?

A

Ribosomes are small cytoplasmic granules found in all cells. They may occur in the cytoplasm or be associated with the rough endoplasmic reticulum.

39
Q

What are 80S ribozymes?

A

They are found in eukaryotic cells, and around 25 nm in diameter

40
Q

What are 70S ribozymes?

A

They are found in prokaryotic cells, mitochondria and chloroplasts, they are slightly smaller than 80S

41
Q

How many subunits do ribozymes have?

A

Ribosomes have two subunits one large and one small each of which contains ribosomal RNA and protein.

42
Q

What is the cell wall?

A

The cell wall is a characteristic of all plant cells, the cell wall consists of microfibrils of the polysaccharide Cellulose, embedded in a matrix.

43
Q

What characteristics of the cell wall are there?

A

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 cells walls and cement adjacent cells together.

44
Q

What are the functions of the cell wall?

A

To provide mechanical strength in order to prevent the cell bursting under the pressure created by the osmotic entry of water.

To give the chemical 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

45
Q

What are the cell Walls of algae made of?

A

Cell walls of algae are made up of either Cellulose or glycoproteins, or a mixture of both.

46
Q

What are the cell walls of fungi made up from?

A

The cell walls of fungi do not contain Cellulose but comprise a mixture of nitrogen containing polysaccharide called chitin, a polysaccharide called glycan and Glycoproteins

47
Q

What are vacuoles?

A

A fluid filled sac bounded by a single membrane may be termed a vacuole

48
Q

What is the name of the single membrane surrounding vacuole?

A

The single membrane around it is called The tonoplast.

49
Q

What is inside of the vacuole?

A

A plant vacuole contains a solution of mineral salts, sugars, amino acids, wastes and sometimes pigments such as anthocyanins.

50
Q

What are the functions of a plant vacuole?

A

They support herbaceous plants, and herbaceous parts of woody plants, by making cell is turgid.

The sugars and amino acids might act as a temporary food store.

The pigments my colour petals to attract pollinating insects.

51
Q

State in which process ribosomes are important.

A

Protein synthesis.

52
Q

List three carbohydrates that are absorbed by an epithelial cell of the small intestines.

A

Glucose, fructose, galactose.

53
Q

State the organelle that is being referred to in each of the following descriptions

Possesses structures called Cristae

It contains chromatin

It synthesises glycoproteins

It’s digests worn out organelles

A

Mitochondria

Nucleus

Golgi apparatus

Lysosome

A-Level Bio (14 decks)

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