2. Cells - Eukaryotic Cell Structure Flashcards by Lola Barden

What is the nuclear envelope?

It is a double membrane that surrounds the nucleus.

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What is the nuclear envelope’s outer membrane continuous with?

The endoplasmic reticulum of the cell.

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What is the function of the nuclear envelope?

It controls the entry and exit of materials in and out of the nucleus and contains the reactions taking place within it.

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What is the function of nuclear pores?

They allow the passage of large molecules, such as messenger RNA, out of the nucleus.

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What is the nucleoplasm?

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

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What do chromosomes consist of?

Protein-bound, linear DNA.

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What is the nucleolus?

A small spherical region within the nucleoplasm.

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What is the function of the nucleolus?

It manufactures ribosomal RNA and assembles the ribosomes.

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What are the 3 functions of the nucleus?

Act as the control centre of the cell through the production of mRNA and tRNA and hence protein synthesis
Retain the genetic material of the cell in the form of DNA and chromosomes
Manufactures ribosomal RNA and ribosomes

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What surrounds the mitochondrion and why?

A double membrane to control the entry and exit of material.

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What is special about the inner membrane of the two membranes surrounding the mitochondion?

It’s folded to form extensions known as cristae.

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What are cristae?

They are extension of the inner membrane of the mitochondrion.

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What is the function of cristae?

They provide a large surface area for the attachment of enzymes and other proteins involved in respiration.

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What makes up the remainder of the mitochondrion? What is its function?

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

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What is the function of mitochondrion?

They are the sites of the aerobic stages of respiration in a cell. They are responsible for the production of ATP needed for processes such as active transport.

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What is the chloroplast envelope?

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

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What are the grana in chloroplasts?

They are stacks of up to 100 disc-like structures called thylakoids.

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What is found within the thylakoids?

The photosynthetic pigment called chlorophyll.

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What do some thylakoids have that do what?

Some thylakoids have tubular extension that join up with thylakoids in adjacent grana.

What is the function of the grana?

It’s where the first stage of photosynthesis (light absorption) takes place.

What is the fluid-filled matrix in the chloroplasts called?

The stroma.

What is the function of the stroma?

It’s where the second stage of photosynthesis (synthesis of sugars) takes place.

Name one other structure that is found within the stroma:

Starch grains.

Give 3 ways how chloroplasts are adapted to their function of harvesting sunlight and carrying out photosynthesis:

The granal membranes provide a large surface area for the attachment of chlorophyll, electron carriers and enzymes that carry out the first stage of photosynthesis
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

What is the endoplasmic reticulum?

It’s an elaborate, three-dimensional system of sheet-like membranes that spread through the cytoplasm of the cells.

What does the endoplasmic reticulum enclose?

A network of tubules and flattened sacs called cisternae.

What are the two types of ER?

- Rough endoplasmic reticulum (RER) - Smooth endoplasmic reticulum (SER)

What is the main difference between the RER and the SER?

THE RER has ribosomes present on the outer surface of the membranes, whereas the SER lacks ribosomes on its surface and is often more tubular in appearance.

What are the 2 functions of the RER?

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

What are the 3 functions of the SER?

a) Synthesise, store and transport lipids b) Synthesise, store and transport carbohydrates c) Detoxifying chemicals and metabolising drugs, particularly in liver cells

What does the Golgi apparatus consist of?

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

Where are the proteins and lipids produced by the ER passed through in strict sequence?

The Golgi apparatus.

What are the 5 functions of the Golgi apparatus?

- Add carbohydrates to proteins to form glycoproteins (modifying proteins) - 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

What else does the Golgi apparatus do to proteins?

It ‘labels’ them, allowing them to be accurately sorted and sent to their correct destinations.

How are lysosomes formed?

When the vesicles produced by the Golgi apparatus contain enzymes such as proteases and lipases.

What are the 4 functions of lysosomes?

- 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 the useful chemicals they are made of can be re-used - Completely break down cells after they have died (autolysis)

What are ribosomes?

They are small, cytoplasmic granules found in all cells.

What are the two types of ribosomes?

- 80S - found in eukaryotic cells - 70S - found in prokaryotic cells, mitochondria and chloroplasts, is slightly smaller

What are ribosomes the site of?

Protein synthesis

What are two features of the plant cell wall?

- 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

What are 3 functions of the cell wall?

- 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

What is a vacuole?

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

What is the single membrane surrounding the vacuole called?

The tonoplast.

What does a plant vacuole contain?

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

What are 3 functions of the vacuole?

- They support herbaceous plants by making cells turgid - The sugars and amino acids may act as a temporary food store - The pigments may colour petals to attract pollinating insects