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Cell structure > Eukaryotic cell structure > Flashcards

Eukaryotic cell structure Flashcards

1
Q

Name all the parts to a eukaryotic cell nucleus and draw and label.

A
  • Nuclear envelope.
  • Nuclear pores.
  • Nucleoplasm.
  • Chromosomes.
  • The nucleolus.
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2
Q

What’s the role of the nuclear envelope in the nucleus?

A
  • A double membrane that surrounds the nucleus.
  • Its outer membrane is continuous with the endoplasmic reticulum of the cell and often has ribosomes on it.
  • Controls entries and exits of materials in and out of the nucleus.
  • Contains the reactions taking place within it.
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3
Q

What’s the role of the nuclear pores in the nucleus?

A
  • Allows large molecules e.g. mRNA out of the nucleus.

- There are about 3000 pores in each nucleus, 40-100nm in diameter.

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4
Q

What’s the role of the nucleoplasm in the nucleus?

A
  • The granular, jelly-like material inside of the nuclear membrane or nuclear envelope
  • Made up mostly of water, a mixture of various molecules, and dissolved ions.
  • It helps to maintain the shape of the nucleus.
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5
Q

What’s the role of the chromosomes in the nucleus?

A
  • Consists of protein bound, linear DNA.
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6
Q

What’s the role of the nucleolus in the nucleus?

A
  • A small spherical region within the nucleoplasm.
  • Manufactures rRNA and assembles the ribosomes.
  • There might be more than one nucleolus in a nucleus.
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7
Q

What is the function of the nucleus?

A
  • Acts as a control center of the cell through the production of mRNA and tRNA hence protein synthesis.
  • Retain the genetic material of the cell in forms of DNA and chromosomes.
  • Manufacture rRNA and ribosomes.
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8
Q

Name all the structures in the mitochondrion and draw and label the structure.

A
  • A double membrane.
  • Cristae.
  • Matrix.
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9
Q

What is the role of the double membrane in the mitochondrion?

A
  • Controls entry and exit of material.

- The inner part of the double membrane is folded to form extensions known as cristae.

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10
Q

What is the role of the cristae in the mitochondrion?

A
  • They are extensions of the inner membrane, in some species, it goes across the whole width of the mitochondrion.
  • They provide a LARGE SA for the attachment of enzymes and other proteins involved in respiration.
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11
Q

What is the role of the matrix in the mitochondrion?

A
  • It makes up the rest of the mitochondrion.
  • Contains protein, lipids, ribosomes, and DNA which allows mitochondrion to control the production of some of their own proteins.
  • Many enzymes that are involved in respiration are found in the matrix.
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12
Q

Why are mitochondria important for our body?

A
  • They are the sites of the aerobic stages of respiration. so they are responsible for the production of ATP from respiratory substrates e.g. glucose.
  • Due to this, the number and size of mitochondria and their number of cristae are high in cells which has high levels of metabolic rate who requires a plentiful supply of ATP. E.g. muscle and epithelial cells- EC need a lot of ATP for absorbing substances from the intestines by active transport.
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13
Q

What are chloroplasts?

A

Organelles that carry out photosynthesis.

They vary in shape but usually disc-shaped, 2-10um long and 1um in diameter.

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14
Q

Draw and label the structure of the chloroplast and list the features within it.

A
  • The chloroplast envelope.
  • The grana.
  • The stroma.
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15
Q

What is the role of the chloroplast envelope in the chloroplast?

A
  • It’s the double plasma membrane which surrounds the organelle.
  • It’s highly selective in what it allows to enter and leave the chloroplast.
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16
Q

What is the role of the grana (granum sing.) in the chloroplast?

A
  • Grana are stacks of up to 100 disc-like structures called thylakoids.
  • Within the thylakoids it contains chlorophyll.
  • Some thylakoids have tubular extensions that join up with the thylakoids in adjacent grana.
  • The grana are where the first stage of photosynthesis (light absorption) takes place.
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17
Q

What is the role of the stroma in the chloroplast?

A
  • Stroma is a fluid-filled matrix where the 2nd stage of photosynthesis takes place (synthesis of sugar).
  • Within the stroma, there are other structures e.g starch grains.
  • It’s the solution that surrounds the grana.
18
Q

How are chloroplasts adapted towards taking in sunlight to carry out photosynthesis?

A
  • Many grana, large surface area for photosynthetic pigments, electron carriers and ATP synthase enzymes.
  • Contains chloroplast DNA and ribosomes needed to make proteins for photosynthesis.
  • Stroma - the fluid contains all the enzymes that’s needed for making sugars in the 2nd stage of photosynthesis.
19
Q

What is the endoplasmic reticulum (ER) draw and label?

A
  • ER is a 3-dimensional sheet-like membrane that spreads throughout the cytoplasm of the cell.
  • It continues towards the outer nuclear membrane where the membranes include many tubules and flattened sacs called cisternae.
20
Q

What are the 2 types of ER?

A
  • Rough endoplasmic reticulum - RER - It has ribosomes present on the outer surfaces of the membrane.
  • Smooth endoplasmic reticulum - SER - It lacks ribosomes on its surface and appear to be more tubular shaped.
21
Q

What’re the functions of RER and SER?

A
  • RER - provides a large SA for the synthesis of proteins and glycoproteins (simple protein with sugars attached).
  • Provide a pathway for the transport of materials e.g. proteins throughout the cell.
  • SER - synthesise, store and transport lipids.
  • synthesise, store and transport carbohydrates.
22
Q

Why do cells e.g. liver and secretory cells- epithelial cells that line the intestine have a very extensive ER?

A

They have a very extensive ER because they need to make and store a lot of carbohydrates, proteins, and lipids.

23
Q

Where does the Golgi apparatus occur?

A

It occurs almost in all eukaryotic cells and similar to SER in structure but it’s more compact.

24
Q

What does the Golgi apparatus consist of?

A

Stack of membranes that make up flattened sacs (cisternae), with small rounded structures called vesicles.

25
Q

What does the Golgi apparatus do?

A
  • The proteins produced by the ER is passed through the Golgi apparatus.
  • The Golgi modifies these proteins by attaching a non-protein molecule e.g. carbohydrate.
  • It ‘labels’ them so they can be accurately sorted out and be sent to their correct destination.
  • When they are sorted, the proteins and lipids are transported in Golgi vesicles which are regularly pinched off from the ends of the Golgi cisternae.
  • Those vesicles may move to the cell surface, where they fuse with the membrane and release their contents to the outside.
26
Q

What are the functions of the Golgi apparatus?

A
  • Add carbohydrates to proteins to form glycoproteins.
  • Produce secretory enzymes, e.g. those secreted by the pancreas.
  • Secret carbohydrates e.g. those used in making the cell walls of plants.
  • Transport, modify and store lipids.
  • Form lysosomes.
27
Q

How are lysosomes formed?

A
  • Lysosomes are formed when the vesicles produced by the Golgi apparatus contains enzymes e.g. protease, lipase.
28
Q

What are lysozymes?

A
  • Lysozymes are obtained in the lysosomes, they are the enzymes that hydrolyse the cell walls of certain bacteria.
29
Q

How do lysosomes obtain the enzymes?

A
  • They can contain up to 50 enzymes in a single lysosome
  • They isolate these enzymes from the rest of the cells before releasing them, either to the outside or into a phagocytic vesicle within the cell.
30
Q

What are the functions of a lysosome?

A
  • Hydrolyse materials that are ingested by phagocytic cells e.g. bacteria.
  • Release enzymes to the outside of the cell (exocytosis) so they can destroy the material around the cell.
  • Digest worn out organelles so useful materials they are made of can be re-used.
  • Completely break down cells after they have died (autolysis).
31
Q

What are ribosomes?

A

They are small cytoplasmic granules found in all cells, may occur in the cytoplasm or associated with RER.

32
Q

What are the 2 types of ribosomes?

A
  • 80s - found in eukaryotic cells
  • 70s - found in prokaryotic cells, mitochondria, and chloroplast.
    Ribosomes have 2 subunits- one large and one small, each containing rRNA and proteins.
33
Q

What are the functions of ribosomes?

A
  • Site for protein synthesis.

- They assemble amino acids to form a specific protein.

34
Q

What is the cell wall?

A
  • Found in all plant cells, it consists of microfibrils of polysaccharide cellulose, embedded in a matrix.
  • Cellulose microfibrils are quite strong so it can help yo support the cell wall.
35
Q

What are the features of the cell wall?

A
  • Consists of a number of polysaccharides e.g. cellulose.

- There’s a thin layer - middle lamella which marks the boundary between adjacent cell walls.

36
Q

What are the functions of the cell wall?

A
  • Provide strength to prevent the cell bursting under pressure created by the osmotic entry of water.
  • Give mechanical strength to the plant as a whole.
  • Allow water to pass along it so contributes to the movement of water through the plant.
37
Q

What makes up the cell wall of algae?

A
  • Either cellulose or glycoprotein or both.
38
Q

What makes up the cell wall of fungi?

A
  • Fungi’s cell wall does not contain cellulose but includes a mixture of a nitrogen-containing polysaccharide called Chitin, a polysaccharide called Glycan and Glycoproteins.
39
Q

What are vacuoles?

A
  • Fluid-filled sac bounded by a single membrane.
  • Within matured plant cells, there’s usually a large central vacuole and the single membrane around it is called the tonoplast.
40
Q

What substances does a plant vacuole contain?

A

Solutions of mineral salts, sugars, amino acids, wastes and sometimes pigments e.g. anthocyanins.

41
Q

What are the functions of vacuoles?

A
  • Support herbaceous plants and herbaceous parts of a woody plant, by making them turgid.
  • Sugar and amino acids can act as a temporary food store.
  • Pigments may colour petals to attract pollinating insects.

Cell structure (7 decks)

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