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Biology > 1.2 Ultrastructure of cells > Flashcards

1.2 Ultrastructure of cells Flashcards

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1
Q

How do you calculate magnification?

A

Image size divided by actual size

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2
Q

What are the steps to calculate magnification?

A

Step one: Measure the image size using a ruler in mm
Step two: convert the mm into micrometers (μm)
Step three: divide your answer by the actual size

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3
Q

What are the steps to calculate the actual size of an image?

A

Step one: Measure the image using a ruler in mm
Step two: convert mm into μm
Step three: divide your answer by the magnification

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4
Q

What is the conversion from mm to μm to nm?

A 
1mm = 1000μm
1μm = 10000nm

1mm=1000000nm

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5
Q

What is the total magnification of a light microscope?

A

x1500

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6
Q

What does the photo of the image produced by a light microscope and an electron microscope called?

A

Photomicrograph an electro micrographs

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7
Q

What is the relationship between magnification and resolution

A

Magnification is how zoomed in the pictures and the resolution is how clear it is.
Increasing magnification does not mean increasing resolution.

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8
Q

How do light microscope and electron microscope differ?

A

Light microscope uses a beam of light that is focused by means of glass lenses
Electron microscope uses a beam of electrons focus by magnetic lenses

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9
Q

Where does the sample have to be in an electron microscope to ensure the electron beams travel in straight lines? How does this affect the type of specimen that can be viewed through an electron microscope?

A

Sample has to be in a vacuum so the specimen must be dead so we cannot view living cells in an electron microscope as they would explode.

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10
Q

What structure does light microscope and electron microscope’s reveal?

A

Light microscopes reveal the structure of cells

Electron microscope’s reveal the ultrastructure (organelles) of cells

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11
Q

Why do electron microscopes have a much higher resolution than light microscopes?

A

Electron microscopes have a shorter wavelength so half of its wavelength is the minimum size we can see. Light microscopes have a longer wavelength so it’s half isn’t as small. Therefore, smaller structures than a half of its wavelength cannot be seen.

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12
Q

What are the two fundamental types of cell?

A

Eukaryotic and prokaryotic cell

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13
Q

How many cells can eukaryotes contain and where can DNA be found? What are the organelles surrounded by?

A

Eukaryotes can consist of one or more cells (unicellular or multicellular)
DNA is contained in a membrane bound nucleus
Contain membrane-bound organelles

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14
Q

How many cells can eukaryotes contain and where can DNA be found? What are the organelles surrounded by?

A

Eukaryotes can consist of one or more cells (unicellular or multicellular)
DNA is contained in a membrane bound nucleus
Contain membrane-bound organelles

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15
Q

What type of organisms are classed as eukaryotes?

A

Animals, plants, fungi, protoctist

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16
Q

What is discrete compartment in eukaryotes?

A
  • Discrete compartment means that the organelles are membrane bound, and each organelle is separate from the rest of the cell
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17
Q

What are the advantages of eukaryotic cells being compartmentalize in two separate organelles? EDLM (hint)

A
  • Efficiency of metabolism - enzymes and substrates for a particular process can be much more concentrated than if they were spread throughout the cytoplasm
  • Damaging substances can be isolated - e.g. digestive enzymes of a lysosome could kill a cell if they were not safely stored inside the lysosome membrane
  • Localized conditions - condition such as pH can be maintained at an ideal level for a particular process, which may be different to the levels needed for other processes in a cell
  • Movement of organelles within the cell - depending on the cells requirements
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18
Q

What does the nucleus in eukaryotic cells contain (2)?

How do relatively large molecules pass through?

A
  • Nucleus contains genetic material in the form of chromatin.
    Chromatin is DNA wrapped around histone proteins
  • The nucleolus in the nucleus makes rRNA which is combined with proteins to form ribosomes, which move out of the nucleus to into the cytoplasm.
  • Relatively large molecules are able to pass through due to the nuclear pores in the double membrane nuclear envelope.
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19
Q

What are ribosomes made out of, where and how is it made?

Where can it be found and what is its function?

A
  • Made of ribosomal RNA (rRNA)
  • Made in the nucleolus, as two separate smaller subunits, which pass through the nuclear envelope into the cytoplasm where they combine
  • Function: protein synthesis - mRNA is translated into amino acids
  • Some remain free in the cytoplasm (synthesis protein that will be used inside the cell)
  • Some attached to the exterior of the RER (synthesize proteins that will be exported outside the cell)
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20
Q

What are the types of endoplasmic reticulum?

And what is it? What is a continuous with?

A
  • The endoplasmic reticulum (ER) it’s a network of membranes enclosing fluid–filled flattened sacs called cisternae.
  • It is continuous with the outer membrane of the nuclear envelope
  • There are two types: smooth endoplasmic reticulum (SER) + rough endoplasmic reticulum (RER)
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21
Q

What is the structure of the rough endoplasmic reticulum (RER) and its function?
What is it called it with? What role does the cisternae have? Where do the products go?

A
  • It’s outside is coated was ribosomes, and the cisternae provide large surface area for a ribosomes
  • Its function is protein synthesis - ribosomes assemble amino acids into proteins
  • It has a intracellular (within the cell) transport system - transports proteins that were made on the attached ribosomes through the cisternae to the Golgi apparatus
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22
Q

What is the structure and function of the smooth endoplasmic reticulum (SER)?
What shape is it in? What’s on the surface?

A
  • It is a more tube shape than RER and theres no ribosomes on the surface
  • Function: involved with absorption, synthesis and transport of lipids from the gut, such as: synthesis of cholesterol, phospholipids and steroid hormones
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23
Q

What is the structure and function of the Golgi apparatus?

What do they modify? What do they modify it into? Where does the product when leaving the Golgi apparatus?

A

It is a stack of membrane bound flattened sacs called cisternae

Function:

  • secretory vesicles bring materials to and from the golgi apparatus.
  • modifies lipids from the SER
  • modifies proteins from SER by: adding sugar molecules (to make glycoprotein), adding lipid molecules (to make lipidprotein), and folding them into their 3-D shapes
  • they package the modified proteins into vesicles that are pinched off and then either stored in the cell, or move to the plasma membrane, either to be incorporated into the plasma membrane, or export it outside the cell
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24
Q

What is the structure and function of lysosomes?

Where is the abundant in? How does it help the sperm cell?

A

It is a specialized vesicles formed from the Golgi apparatus. It contains powerful hydrolytic (digestive) enzymes.

Function:

  • engulf and digest old cell organelles and pathogens, returning that I just took components to the cell for used
  • Break down the cell after death (autolysis)
  • Abundant in phagocytic cells (Phagocytes are cells that protect the body by ingesting harmful foreign particles, bacteria, and dead or dying cells)
  • the specialized lysosome (acrosome) in the head of a sperm cell helps it penetrate the egg by breaking down the material surrounding the egg
25
Q

What is the structure of mitochondria and its function?
How does it provide a large surface area? What does it form in return? What is the inner membrane coated it with? What cells is it abundant in?

A
  • It is surrounded by a double membrane. The inner membrane folds inwards (providing a large surface area) add to form the cristae. The cristae project into a liquid called the matrix.
  • The inner membrane is coated in enzymes, which catalyzes the reaction of aerobic respiration to produce ATP.
  • It is abundant in cells where much metabolic activity takes place e.g. liver cells, sperm cells, at snapses.
26
Q

What is the structure and function of chloroplast?

How many membranes? What’s inside?

A
  • Chloroplasts contain thylokoids that give a large surface area needed for the enzymes, proteins and pigment molecules necessary in the process of photosynthesis.
  • The inner and outer membrane make up a double membrane, the space between the membrane is called the inter-membrane space. Stroma is a fluid filled matrix and the matrix has a jelly like structure. There are thylakoids and granum. Each stack of thylakoids is called a granum (grana:plural). The grana are linked together by the internal lamellae, which are thin, flat pieces of thylakoid membrane.
27
Q

What is a vacuole and its function?

What does it contain? What is it important for? What is the membrane?

A
  • Vacuole contains cell sap - a watery solution of different substances, including sugars, enzymes and pigments.
  • Large permanent vacuoles are important in keeping plant cells turgid
  • The membrane of a vacuole is called a tonoplast
28
Q

What is the structure and function of a cytoskeleton?

What are the 3 protein structure is called? What are they like and what do they do?

A

Cytoskeleton is a network of proteins structures within the cytoplasm consisting of:
- microfilaments: (7nm in diameter) small solid strands made of subunits of the protein actin, used for cell movement and contraction

  • intermediate filaments: (10nm in diameter). Provides mechanical strength
  • microtubules: (18-30nm in diameter) - straight cylinders made of subunits of the protein tubulin. It forms tracks along which motor proteins ‘walk’ and move organelles e.g. vesicles around the cell. Forms spindle fibers during cell division. Make up cilia, flagella and centrioles.
29
Q

What is the structure and function of centrioles?

How are used in cell division? How do they help form cilia and flagella?

A
  • It has two bundles of microtubules at right angles to each other. 2 associated centrioles form a centrosome.

Function:

  • before a cell divides, the spindle fiber forms from the centrioles so chromosomes can later be seperated
  • involved in the formation of cilia and flagella. Before the city of form, the centrioles multiply and lineup and if the cell surface membrane. Microtubules and sprout outwards from each centriole, forming a cilium or flagellum.
30
Q

What is the structure and function of cilia and flagella?

Where can they be found? What are they form from and what do they? How do they perform their function?

A
  • They are protrusions (something that sticks out) from the cell surface
  • They contain microtubules
  • Formed from centrioles
  • In cross-section, they have an outer membrane and a ring of 9 pairs of protein microtubules inside, with two microtubules in the middle - the ‘9+2’ formation

Function:

  • Cilia beat in a rhythmic manner, creating a current, and cause fluids or objects adjacent to the cell to move
  • microtubules contract to make flagella move, propelling cells forward
31
Q

What is the function of the exocrine glands of the pancreas?How does the ultrastructure of the exocrine gland cells make them suitable for their function?

A

They secrete digestive enzymes e.g. amylase, lipase, which will digest food in the small intestine.

Ribosome, RER, Golgi apparatus, vescles, microtubles -> help produce, package, secrete

32
Q

List the organelles with a single membrane (5)

List the organelles with a double membrane (3)

A

Single membrane: RER, SER, Golgi apparatus, vesicles and vacuoles
Double membrane: Nucleus, mitochondrion, chloroplasts

33
Q

What do gland cells do? What are the two types called?

A

Plant cells secrete substances – they release them through their plasma membrane.

  • endocrine cells secrete hormones into the blood stream
  • exocrine gland cells in the pancreas secrete digestive enzymes into a duct that carries them to the small intestine where they digest food.
34
Q

How does the exocrine gland cells synthesize proteins (enzymes) in large quantities, call system to make them ready for secretion, transport them to the plasma membrane and then release them?

A

Proteins made with the help of the nucleus be synthesized

35
Q

What is the function of Palisade mesophyll cells?

A

The function of the leaf is photosynthesis - producing organic compounds from carbon dioxide and other simple inorganic compounds, using light energy. The cell type that carries out most photosynthesis in the leaf is Palisade mesophyll. The shape of the cell is roughly cylindrical. Like all living plant cells the cell is surrounded by a cell wall, with a plasma membrane inside it.

36
Q

How can we deduce the function of specialized cells?

A

By interpreting and identifying organelles from electron micrographs?

37
Q

How do eukaryotic organelles work together: Inside the nucleus
What is it made out of? What makes it? What is made?

A

1) DNA stores as chromatin
2) the nucleolus makes ribosomal RNA (rRNA)
3) DNA is transcribed it into mRNA which is a copy of the DNA but one strand

38
Q

How do eukaryotic organelles work together: In the cytoplasm

What does it go?

A

The MRNA travels out the nucleus through the nuclear pore and goes to a ribosomes

39
Q

How do eukaryotic organelles work together: At the ribosomes

Where can they be found (2), whats the difference?

A

Ribosomes exist in two locations within the cell: RER and floating free in the cytoplasm

  • RER: synthesising proteins that will be exported outside the cell. It goes through a packaging process.
  • Free floating ribosomes in the cytoplasm: synthesise proteins used inside the cell

The mRNa goes through the ribosome and translates into proteins (made out of amino acids)

40
Q

Where does transcription and translation happen?

A

Transcription: in nucleus
Translation: In ribosome

41
Q

How do eukaryotic organelles work together: ribosomes on the RER
How does the mRNA enter? What happens when its inside? How and where does it leave to?

A

1) The mRNA in the cytoplasm goes through the ribosome attached to the RER membrane and enters the RER as a protein after being translated
2) The protein is folded
3) Protein is transported along the cisternae
4) Vesicle pinches off
5) Protein in vesicle travels away to the golgi apparatus

42
Q

How do eukaryotic organelles work together: Golgi apparatus

What happens in the golgi apparatus? What are two of its products?

A
  • Protein is modified procesed and packages

Add lipid = lipoprotein
Add sugar = glycoprotein

43
Q

What is exocytosis and endocytosis?

A

Exocytosis: the process of things leaving the cell. The vesicle fuses with the cell surface membrane. Releasing the protein outside the cell

Endocytosis: Proteins can come back in and take some of the membrane to create its own vesicle. Ultimately it goes back to the golgi apparatus and fuses.

44
Q

What does the SER do?

What process is it involved in? Is it the same as RER? What does it not have compared to RER?

A

SER does the same thing as RER but instead of synthesising proteins, it synthesises lipids. e.g. cholesterol, phospholipids, steroids, glycoprotein

There are no ribosomes

45
Q

Where is the code for protein synthesis carried in?

What is the made of?

A

DNA which are made of genes or histones.

46
Q

What does protein synthesis require a lot of? How does it get it?

A

Proteins synthesis require a lot of energy/ATP so the cells contain many mitochondria

47
Q

What is the main difference between prokaryotic cells and eukaryotic cells?

A

Prokaryotic cells are all unicellular and they don’t have a nucleus

Eukaryotic cells can be unicellular or multicellular and they have a nucleus

48
Q

List the features of a bacterium (prokaryotic cell) (4 groups) (8)

A

Flagella, pilli
Plasma membrane, slime capsule, cell wall
Plasmids, 70s ribosomes, nucleoid

49
Q

Which structure of a prokaryotic cell is always present (5)? What are the additional structures that are sometimes present? (6)

A

Always: Plasma membrane, Circular DNA, cytoplasm, ribosome, cell wall

Additional:
Pili - for attachment to other cells or surfaces, involved in sexual reproduction
Plasmid - small circle of DNA, several may be present
Capsule - additional protection
Mesosome - infolding of plasma membrane, associated with DNA during cell division, and helps with formation of new cell walls
Infolding of plasma membrane - may form a photosynthetic membrane, or carry out nitrogen fixation
Flagellum - for locomotion, very simple structure

50
Q

What structures are shared with eukaryotic and prokaryotic? (8)

A

Cytoplasm, cell surface membrane, ribosome, DNA and RNA, vacuoles, flagella (in sperm cell), cytoskeleton (more complex and eukaryotic)

51
Q

What structures from eukaryotic cells never found in prokaryotic cells? (11)

A

Nucleus, nucleolus, RER+SER, golgi apparatus, mitochondrion, lysosome, centrism, chloroplast, cilia, chitin (fungi) and cellulose (plant) cell walls

52
Q

What are structures only found in prokaryotic cells? (2)

What are structures found in some prokaryotic cells?

A

Only: Peptidoglycan cell walls, nucleoid (Circular DNA/chromosomes)

Sometimes: Pili, plasmid, capsule, mesosome, flagellum, unfolding of plasma membrane

53
Q

What is a nucleoid?
What is positioned in it? It is ____ to make it more compact.

What is a plasmid? Where is it?

A

An area within the cytoplasm where the DNA is positioned.
It is super coiled to make it more compact.

Placements or separate tiny circles of DNA carrying only a few genes. Plasmids occur throughout the cytoplasm.

54
Q

What are the genes on a chromosome is often grouped into?

A

Operons meaning a number of genes or switch on or off at the same time.

55
Q

What’s the difference between the ribosomes and eukaryotic and prokaryotic cells? Why is it?

A

Ribosomes in prokaryotic cells are smaller than those in eukaryotic cells

Prokaryotic ribosomes: 70s (20nm in diameter)
Eukaryotic ribosomes: 80s (30nm in diameter)

Eukaryotic cells need more complex proteins and need to make more.

56
Q

What are prokaryotic cell walls made of?

A

Prokaryotic cells have a cell wall made from peptidoglycan, also known as murein. It is a complex polymer formed from amino acids and sugars.

57
Q

How do prokaryotes divide?

A

by binary fission (asexual reproduct)
* single circular choromosome is replicated
* the two copeis of the cohromosome move to opposite ends of the cell
* division of the cytoplasm of the cell quickly follors
* each of the daughter cells contains one copy of the chromosome so they are genetically identical

58
Q

When drawing eukaryotic and prokaryotic cells how many labels to include for each?

A

Eukaryotic: 8 (plasma membrane, nucleus, lysosome, mitochondria, cytoplasm, free ribosome, RER, Golgi apparatus)

Prokaryotic: 7 (70s ribosomes, plasmid, pillow, nucleoid, capsule, cell wall, plasma membrane

Biology (57 decks)

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