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Foundation to Bioscience 1 > Organelles > Flashcards

Organelles Flashcards

1
Q

What are the two over-arching types of cell?

A

Eukaryotic and prokaryotic

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2
Q

Which category do animal cells fall into?

A

Eukaryotic cells

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3
Q

What’s the main difference between eukaryotic and prokaryotic cells?

A

Eukaryotic cells have a membrane bound nucleus

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4
Q

Why do organelles have membranes?

A

In order to create and maintain a specific environment, which is important for reactions that require a specific pH for example

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5
Q

Why are cells the basic unit of life, not organelles?

A

Cells are the smallest part of an organism that retains characteristics of the entire organism. They function on a micro level how their tissue functions on a macro level

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6
Q

Give 6 functions of cells

A 
Communication
Movement
Growth
Protection and support
Cell metabolism and energy release
Inheritance
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7
Q

What do all animal cells have at some stage in their life-cycle? (3)

A

A plasma membrane, the cytoplasm, a nucleus

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8
Q

Do all cells have the same ratio of organelles?

A

No- it depends on the cell type. Not all organelles are present in all cell types

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9
Q

Why is the plasma membrane important for cells?

A

It separates the intracellular environment from the extracellular. It also determines what moves in and out of the cell by selective permeability.

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10
Q

Briefly describe the structure of the plasma membrane.

A

The membrane is made up of phospholipids, which form a bilayer. A bilayer is formed because the phosphate heads are hydrophilic, and the lipid tails are hydrophobic. There are also transmembrane channels, proteins, and carbohydrates

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11
Q

How is the membrane potential maintained?

A

Regulating ion movement across the membrane results in a difference in charge- one side is more positive than the other.
The membrane potential is very noticeable in nerve cells.

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12
Q

What is the cytoplasm composed of?

A
  • The cytosol, which is the fluid part of the cytoplasm. It contains dissolved substances like ions, cytoskeleton, and cytoplasmic inclusions.
  • Organelles, which are specialised structures within the cell. They can’t exist outside of cells
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13
Q

What is the function of the cytoskeleton?

A

It supports the cell and holds the nucleus and other organelles in place

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14
Q

What are organelles?

A

Specialised structures within the cell that perform specific functions. In eukaryotic cells, the organelles are bound by lipid bilayers- to control transport and communication

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15
Q

What is the function of mitochondria?

A

They are the site of respiration, so they provide energy for the cell in the form of ATP.

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16
Q

Describe the structure of mitochondria

A

It’s double membrane bound, with the outer membrane being smooth and inner membrane being folded. The matrix is enclosed by the inner membrane.

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17
Q

Why are mitochondria described as semi-autonomous?

A

They can move around the cell, divide, and fuse without direct orders from the nucleus.

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18
Q

What’s special about mitochondrial DNA?

A

It’s inherited only from the maternal line. It means scientists can use it to create migration maps. Scientists have used it to find a mitochondrial Eve, who lived about 200,000 years ago in Africa

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19
Q

What’s the issue with mtDNA only being inherited from the mother?

A

Any mutations the mother has will always be expressed in her children. Mitochondrial diseases can be life-threatening.

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20
Q

What’s the most extensive organelle in many cells?

A

The endoplasmic reticulum

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21
Q

Describe the general structure of the ER

A

Broad flattened and interconnected sacs, and tubules. The interior of the tubules are called cisterns. They are surrounded by a phospholipid bilayer membrane

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22
Q

What’s the difference between the structure of rough ER and smooth ER?

A

Rough ER has ribosomes on the outside, making it look rough; smooth ER doesn’t have ribosomes attached

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23
Q

What are the main functions of ER?

A
  • Detoxification of drugs and alcohol by the addition of a carboxyl group
  • Storage of newly synthesised molecules
  • Transport of molecules
  • Smooth ER: lipid production & carbohydrate metabolism
  • Rough ER: synthesis of proteins for secretion
24
Q

Why are ribosomes attached to the rough ER?

A

Ribosomes are the site of protein production. The proteins then make their way through the rough ER, where they are modified. For example sugar groups and metal groups can be added to the protein chain.

25
Q

Where are calcium ions stored in muscle cells?

A

In the smooth ER

26
Q

Describe the structure of the Golgi apparatus

A

It consists of one or more stacks of membrane bound cisternae, found close to the nucleus. The lumen of the cisternae are separate from each other

27
Q

What are the main functions of the Golgi apparatus?

A
  • It receives molecules from the ER, modifies them, and exports them to a variety of destinations
  • It packages membrane proteins in vesicles and sends to their required location
  • It also produces enzymes that are found in the lysosomes
28
Q

What are the two faces of the Golgi apparatus?

A

The cis face, which faces the nucleus/ER so it can receive stuff, and the trans face, which faces towards the edge of the cell and it’s where stuff leaves the Golgi apparatus

29
Q

Describe the function of the centrosome

A

The purpose of the centrosome is to help organise microtubules to be utilised during cell division. It also works to use the microtubules to create part of the cytoskeleton of the cell. This helps give the cell its structure.

30
Q

Describe the structure of centrosomes

A

It contains two centrioles arranged perpendicular to each other. Centrioles are made up of microtubules and are found close to the nucleus.

31
Q

What is the function/purpose of the nucleus?

A
  • It contains all the cell’s DNA
  • It contains the machinery to replicate DNA, and to synthesise RNA
  • It controls when to grow and divide, what to metabolise, and what proteins to make
32
Q

How are nuclear pores formed?

A

The nucleus is surrounded by a double membrane. There are many places where the two membranes are fused together to form nuclear pores

33
Q

Why are nuclear pores needed?

A

Nuclear pores are very small and have selective permeability. This selective permeability allows RNA and ribosomes to be transported into the cytoplasm, and certain proteins to be transported into the nucleus, in order to protect it

34
Q

What is the nucleoskeleton?

A

Protein-based structures that give the nucleus shape and mechanical properties

35
Q

Where is the nucleolus found?

A

It’s a dense region within the nucleus. It’s the only eukaryotic organelle without a membrane

36
Q

Describe the function of the nucleolus

A

The nucleolus produces rRNA, which gets converted into ribosomes with the addition of proteins

37
Q

Describe the structure of ribosomes

A

Ribosomes are made up of two subunits- a large subunit and a small subunit.

38
Q

Give the function of ribosomes

A

They are the site of protein synthesis. mRNA is sent from the nucleus to ribosomes with the instructions for making proteins

39
Q

What are the two types of ribosomes? Give the difference in their functions

A
  • Free ribosomes produce the proteins used within the cell

- Bound ribosomes produce the proteins that are packaged and secreted, incorporated into the plasma membrane

40
Q

What is chromatin?

A

Chromatin is the delicate filament found in the nucleus that is formed from dispersed chromosomes

41
Q

Give the main functions of the cytoskeleton

A
  • It supports the cell
  • It holds the organelles in place
  • Helps in movement of the organelles
  • Is responsible for changes in shape of the cell.
42
Q

Name the three filaments that make up the cytoskeleton

A
  • Intermediate filaments, which are flexible but resist strain
  • Microtubles, which are made out of tubulin,
  • Actin, which are microfilaments that are highly organised in muscle cells
43
Q

Why are actin filaments also known as microfilaments?

A

They are the smallest of the three cytoskeleton filaments

44
Q

How are actin filaments arranged in the cytoplasm?

A

They form bundles, sheets or networks

45
Q

Why are the walls of the small intestine covered in microvilli?

A

They extend the walls of the small intestine into the lumen, which increases the amount of nutrients absorbed

46
Q

What is the function of the intermediate filaments?

A

They help with the mechanical stability of cell as they are so long. They also make up the extension of nerve cells

47
Q

What does it mean that the intermediate filaments are stable?

A

They have a permanent structure instead of a dynamic structure like actin or microtubles

48
Q

What are microtubules?

A

Hollow tubes, made up primarily of tubulin. They provide support and structure to the cytoplasm of the cell. Transports intercellular materials by providing tracks for organelles and chromosome movements .

49
Q

Why are microtubules able to maintain a cell’s polarity?

A

They have a positive end and a negative end

50
Q

What are cilia and flagella?

A

They are microtubule based protrusions that grow from centrioles that have moved to the cell membrane.

51
Q

Describe the general structures of cilia and flagella

A

The microtubules are arranged in a circle of 9-2 pairs around a central pair

52
Q

How is the movement of the cilia and flagella produced?

A

The two arms of each pair move past each other, which requires energy from ATP

53
Q

Describe the role of cilia in cells

A

They are small projections on cell surfaces, particularly in the respiratory tract and female reproductive tract. They “beat” in a co-ordinated fashion to move mucus and trapped particles away from the lungs

54
Q

What are the main differences between cilia and flagella?

A
  • Flagella are the larger singular version of cilia.
  • Flagella moves the entire cell rather than cilia moving small particles along the cell wall.
  • The movement of flagella is more wavelike
55
Q

Which is the only mammalian cell type to have flagella?

A

Sperm cells. Most of the energy comes the metabolism of fructose, which takes place in the mitochondria located in the sperm’s midpiece

Foundation to Bioscience 1 (8 decks)

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