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AS Level Biology > 1. CELL STRUCTURE > Flashcards

1. CELL STRUCTURE Flashcards

1
Q

Substance bacterial cell walls are made of

A

peptidoglycan (murein).

–> these are long molecules containg peptides and sugars

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2
Q

What is energy required for in a cell

A
  • active transport
  • movement
  • endocytosis/exocytosis
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3
Q

What are cells with a high demand of energy

A
  • liver cells

- muscle cells

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4
Q

What happens to metabolism when you exercise

A
  • number of mitochondria increase

- so metabolism increases

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5
Q

What are the functions of mitochondria

A
  • aerobic respiration

- synthesis of lipids

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6
Q

What is the process of conversion of ATP to ADP

A

hydrolysis

- the ADP can then be recycled back to the mitochondrion for conversion back to ATP during aerobic respiration

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7
Q

What is responsible for the shape of the cell

A

cytoskeleton made of microtubules along with actin and intermediate filaments

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8
Q

What are the functions of microtubules

A
  • mechanical function of support
  • part of cytoskeleton which determines cell shape
  • secretory vesicles and other organelles can be transported along the outside surfaces of microtubules
  • membrane-bound organelles are held in place by the cytoskeleton
  • during nuclear division, the spindle used for the separation of chromatids is made of microtubules
  • microtubules form part of the structure of centrioles
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9
Q

What is the endoplasmic reticulum

A
  • membranes form an extended system of flattened compartments in the cell, called sacs
  • process can take place inside these sacs, separated from the cytoplasm
  • sacs can be interconnected to form a complete system (reticulum)
  • the ER is continuous with the outer membrane of the nuclear envelope
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10
Q

What are ribosomes made of

A

RNA and protein

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11
Q

Function of the smooth ER

A

production of

  • lipids
  • steroids, such as cholesterol and the reproductive hormones such as oestrogen and testosterone
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12
Q

Where are lipids synthesised

A

smooth ER and mitochondria

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13
Q

Where are reproductive hormones made

A

smooth ER

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14
Q

What happens to proteins made in the rough ER

A
  • proteins made in ribosomes on the rough ER enter the sacs and move through them
  • the proteins are often modified in some way on their journey
  • small sacs called vesicles can break off from the ER and these can join together to form the golgi body
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15
Q

What is the maximum resolution of a light microscope

A

200 nm

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16
Q

What ways do golgi bodies modify the molecules

A
  • addition of sugar molecules to proteins to make glycoproteins
  • removal of first amino acid, methionine, to make functioning protein
  • addition of prosthetic groups such as heam to form proteins with quaternary structure
  • in plants, enzymes in the golgi body convert sugars into cell wall components
  • golgi vesicles are used to make lysosomes
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17
Q

Where are lysosomes made

A

golgi vesicles containing hydrolytic enzymes

18
Q

What organelles have double membranes

A

nucleus
mitochondria
chloroplast

19
Q

Functions of lysosomes

A
  • digestion of mammary glands after lactation
  • digestion of bacteria by phagocytosis forming phagolysosomes
  • replacement of cartilage with bone during development by releasing enzymes outside the cell
  • digestion of a path to the ovum by the acrosome
20
Q

What is the acrosome

A

a lysosome

21
Q

Properties of the ATP molecule

A

small, soluble
can be hydrolysed easily as it is very unstable
releases a lot of energy when hydrolysed

22
Q

How is the size of ribosomes measured

A
  • in ‘S units’

- which are a measure of how fast they sediment in a centrifuge

23
Q

Evidence of endosymbiosis of mitochondria and ribosomes

A
  • contain 70s ribosomes like those found in bacteria
  • contain small, circular (loop of) DNA molecules like those found in bacteria
  • replicate independently of cell division by dividing into two
24
Q

Where are ribosomes found in a cell

A

rough endoplasmic reticulum
cytoplasm
mitochondria
chloroplasts

25
Q

Tissues where microvilli are present

A
  • absorption in the gut

- reabsorption in the proximal convoluted tubules of the kidney

26
Q

What are responsible for an intracellular transport system

A

microtubules

27
Q

Organelles not present in plant cells

A

microvilli
centrioles/centrosome
flagella/cilia
lysosomes

28
Q

What is a centriole

A
  • a hollow cylinder about 500nm long
  • formed from a ring of short microtubules
  • each centriole contains nine triplets of microtubules
29
Q

What are MTOCs

A

the assembly of microtubules from tubulin molecules is controlled by special locations in cells called MTOCs
eg: centrosome in animal cells
basal bodies

30
Q

Substances leaving through the nuclear pores

A

mRNA and ribosomes for protein synthesis

31
Q

Substances entering through the nuclear pores

A

proteins for the synthesis of ribosomes, nucleotides, ATP and some hormones

32
Q

Function of the nucleolus

A

makes ribosomes using the information in its own DNA

33
Q

Why do cells need to be stained

A

because many of the cell contents are colourless or transparent so they need to be stained to be seen

34
Q

How is movement through the plasmodesmata controlled

A

by the structure of the pores in the cell wall

35
Q

Functions of vacuoles

A
  • storage of mineral salts, sugars and other organic substances
  • regulation of osmotic potential
  • storage of pigments such as the red pigments of beetroots
36
Q

Main function of chloroplasts

A

absorption of light during photosynthesis

37
Q

Why do chloroplasts contain a complex system of membranes

A

because the production of ATP requires electron transport in membranes

38
Q

How are chloroplasts adapted to their function

A
  • complex system of membranes for electron transport
  • both the chloroplasts and the membranes can change their orientation within the cell to receive maximum amount of light
39
Q

What are the reserves of lipids in chloroplasts

A
  • reserves for making membranes

- from the breakdown of membranes

40
Q

Function of ribosomes in protein synthesis

A
  • translation occurs in ribosomes
  • provides binding site for mRNA
  • provides binding site for two tRNA molecules
  • two amino acids are held close together and a peptide bond formed by peptidyl transferase
  • allows assembly of amino acids
41
Q

Smooth endoplasmic reticulum

A
  • site of synthesis of triglycerides and lipids as well as cholesterol and steroids
  • is membranous
  • has fluid filled channels
  • has cisternae that are interconnected to each other
  • not associated with ribosomes

AS Level Biology (10 decks)

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