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Biology OCR A - A-level > 1- Cell structure and microscopy > Flashcards

1- Cell structure and microscopy Flashcards

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1
Q

What is a nucleus?

A

contains DNA base sequences that control the activities of the cell

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2
Q

What is a nucleolus?

A

A region in the nucleus where ribosomes are made

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3
Q

What is a nuclear envelope?

A

A double membrane that surrounds the nucleus. It contains pores to allow small molecules to pass to the cytoplasm.

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4
Q

What is rough endoplasmic reticulum?

A

A large surface area for ribosomes to do protein synthesis

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5
Q

What is smooth endoplasmic reticulum?

A

Synthesises lipids

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6
Q

What is the golgi apparatus?

A

Fluid filled membrane bound sacs that modify and package from RER and SER into vesicles

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7
Q

What are ribosomes?

A

Responsibe for the translation of RNA into proteins. In the RER or cytoplasm.

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8
Q

What is mitochondria?

A

The site of ATP production in aerobic respiration. It has a large SA for respiration

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9
Q

What are Lysosomes?

A

They contain digestive enzymes that engulf and destroy old and foreign materials

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10
Q

What are Chloroplasts?

A

The site of photosynthesis. Thylakoid membranes stacked into grana and linked by lamellae

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11
Q

What is a plasma membrane?

A

Phospholipid bi-later with cholesterol regulating fluidity

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12
Q

What are Centrioles?

A

Microtubules that form spindle fibres in mitosis

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13
Q

What is a Cell wall?

A

Made of cellulose (plants), chitin (fungi) or murein (prokaryotes) and provides support to the cell

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14
Q

What is Flagella?

A

A tail structure made of microtubules (sperm)

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15
Q

What is cilia?

A

Microtubukes contract to allow movement (epithelial cells)

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16
Q

What is a vacuole?

A

An organelle that stores cell sap and keeps a plant cell turgid

17
Q

What do ribosomes do? Where are they located?

A

Translate mRNA into a polypeptide chain. Located on RER or in cytoplasm

18
Q

What does RER do to polypeptide chains?

A

Folds them and transports them to golgi in vesicles

19
Q

What does the Golgi apparatus do?

A

Modifies and processes proteins before packaging and sending them to where they are required

20
Q

What is the cytoskeleton?

A

A network of protein threads arranged into microfilaments and microtubules.

21
Q

What does the cytoskeleton help with?

A

Strengthening cell and maintaining shape

22
Q

4 main differences between eukaryotes and prokaryotes

A

1) Prokaryotes have no membrane-bound organelles; eukaryotes do
2) Prokaryotes are smaller than eukaryotes
3) Prokaryotes have circular DNA; eukaryotes are wrapped around chromosome
4) Prokaryotes have smaller ribosomes (70s) than eukaryotes (80s)

23
Q

What are plasmids?

A

Small circular rings of DNA in a prokaryote

24
Q

What are mesosomes?

A

Folded portions of a prokaryotes inner membrane

25
Q

What are pilli?

A

Hair-like structures on a plasma membrane for cellular communication

26
Q

What are the features of a light microscope?

A
  • 1500x actual size
  • 0.2um resolution
  • 2D image
  • Can’t see smaller organelles
    -Can visualise living cells
27
Q

What are the features of a laser-scanning confocal microscope?

A
  • Clearer images
  • Uses laser beam
28
Q

What are the features of a transmission electron microscope (TEM)?

A
  • 1,000,000x actual size
  • 0.0002um resolution
  • living cells cannot be seen
  • 2D
29
Q

What are the features of a scanning electron microscope (SEM)?

A
  • 500,000x actual size
  • 0.002um resolution
  • Living cells cannot be seen
  • 3D
30
Q

What is the magnification?

A

How many times larger the image is compared to the actual object

31
Q

What is the resolution?

A

How well a microscope can distinguish between two points close together

32
Q

What is the magnification equation?

A

I
AM

33
Q

What are the steps to calibrating the eyepiece graticule?

A

1) Place stage micrometer on stage so you can see divisions
2) Align eyepiece graticule with stage micrometer
3) Take away stage micrometer and add sample

34
Q

What are the steps to preparing a specimen to view?

A

1) Add a drop of water to the slide and add thin layer of cells
2) Add a drop of a stain to visualise cells
3) Add a cover slip
4) Place on the stage and select the lowest objective lens
5) Use coarse adjustment to focus
6) Select increasingly higher magnification until you can visualise the structures you are interested in

Biology OCR A - A-level (24 decks)

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