Cell Structure Flashcards

1
Q

Prokaryotic and Eukaryotic

What are the two types of cells?

A

Eukaryotic- contains a nucleus.
Prokaryotic- does not contain a nucleus and is much smaller.

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2
Q

Prokaryotic and Eukaryotic

How is DNA stored in a prokaryotic cell?

A

-Plasmids
-Loops

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3
Q

Animal and plant cells

List the components in both plant and animal cells and their functions.

A

-Nucleus= controls the cell’s activity and contains DNA
-Cytoplasm= site of chemical reactions
-Cell membrane= controls what enters and exits the cell
-Mitochondria= Where respiration happens
-Ribosomes= Protein synthesis

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4
Q

Animal and plant cells

List the additional components in plant cells.

A

-Cell wall= Extra support
-Vacuole= Contains cell sap, keeps the cell turgid
-Chloroplasts= Photosynthesis

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5
Q

Cell specialisation

What is specialisation?

A

When cells adapt to perform a specific function.

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6
Q

Cell specialisation

Sperm cell specialisation.

A

Haploid nucleus- contains genetic information.
Tail- movement.
Mitochondria- provides energy for tail movement.
Acrosome- contains enzymes that digest the egg cell membrane.

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6
Q

Cell specialisation

Nerve cell specialisation.

A

Long axon- allows electrical impulses to be transmitted all over the body from the central nervous system.
Dendrites- from the cell body connect to and receive impulses from other nerve cells, muscles and glands.
Myelin sheath- insulates the axon and speeds up the transmission of impulses along the nerve cell.

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7
Q

Cell specialisation

Muscle cell specialisation.

A

Arrangement of protein filaments- allows them to slide over each other to produce muscle contraction.
Mitochondria- provide energy for muscle contraction.
Merged cells in skeletal muscle- allow muscle fibre contraction in unison.

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8
Q

Cell specialisation

Root hair cell specialisation.

A

Large surface area- absorbs water and nutrients from the surrounding soil.
Thin walls- don’t restrict water absorption.

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9
Q

Cell specialisation

Xylem cell specialisation.

A

No upper or lower margins between cells- to provide a continuous route for water to flow.
Thick, woody side walls- strengthen their structure and prevent collapse.

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10
Q

Cell specialisation

Phloem cell specialisation.

A

Sieve plates- let dissolved amino acids and sugars be transported up and down the stems.
Companion cells- provide the energy needed for active transport of substances along the phloem.

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11
Q

Cell differentiation

What is cell differentiation and why is it important?

A

The process by which cells become specialised. It is important because it allows the production of different tissues and organs that perform various vital functions in the human body.

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12
Q

Cell differentiation

What is the purpose of cell division in mature animals?

A

Repair and replacement of cells.

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13
Q

Cell differentiation

What changes does a cell go through as it differentiates?

A

Becomes specialised through acquisition of different sub-cellular structures to enable a specific function to be performed by the cell.

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14
Q

Microscopy

Define magnification.

A

The number of times bigger an image appears to the size of the real object.

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15
Q

Microscopy

Define resolution.

A

The smallest distance between two objects that can be distinguished.

16
Q

Microscopy

How does a light microscope work?

A

Passes a beam of light through a specimen which travels through the eyepiece lens, allowing the specimen to be observed.

17
Q

Microscopy

What are the advantages of light microscopes?

A
  • inexpensive
  • easy to use
  • portable
  • observe both living and dead specimens
18
Q

Microscopy

What are the disadvantages of light microscopes?

A
  • Limited resolution
19
Q

Microscopy

How does an electron microscope work?

A

It uses a beam of electrons which are focused using magnets. The electrons hit a flourescent screen which emits visible ligh, producing an image. \

20
Q

Microscopy

What are the advantages of electron microscopes?

A
  • Greater magnification
  • Greater resolution
21
Q

Microscopy

How have electron microscopes enabled scientists to dveleoping their understanding of cells?

A
  • Allow small sub-cellular structures to be observed in detail
  • Enable scientists to develop more accurate explanations about how cell structure relates to function
22
Q

Microscopy

What are the disadvantages of electron microscopes?

A
  • Expensive
  • Large so less portable
  • Requires training to use
  • Only dead specimens can be observed
23
Q

Microscopy

How can magnification be calculated?

A

image size / actual size

24
Q

Culturing microorganisms

How do bacteria multiply and how often?

A
  • Binary fission
  • Once every 20 mins if enough nutrients are available and the temperature is suitable
25
Q

Culturing microorganisms

State 2 ways in which bacteria can be grown.

A
  • Nutrient broth solution
  • Colonies on an agar gel plate
26
Q

Culturing microorganisms

Describe the preparation of an uncontaminated culture using aseptic techniques.

A
  1. Use pre-sterilised plastic petri dishes or sterilise glass petri dishes and agar gel before using with an autoclave
  2. Pour the sterile agar gel into the petri dish and allow time to set
  3. Sterilise the inoculating loop by passing it through a bunsen burner flame
  4. Dip the inoculating loop into the solution of microorganisms and make streaks with the loop on the surface of the agar
  5. Put the lid on the petri dish and secure it with tape. Label accordingly then turn and store upside down
  6. Incubate the culture at 25’C in school laboratories
27
Q

Culturing microorganisms

Why must petri dishes and equipment be sterilised before use?

A

To kill any bacteria already present.

28
Q

Culturing microorganisms

Why must the petri dish lid be secured with tape and stored upside down?

A
  • Stops bacteria in the air contaminating the culture
  • The lid is not fully sealed to prevent the growth of anaerobic bacteria in a lack of oxygen
  • Upside down to prevent condensation from forming and dripping down onto the colonies
29
Q

Culturing microorganisms

What is the formula used to calculate cross-sectional area of a bacterial colony or clear area around a bacterial colony?

A

πr^2

30
Q

Culturing microorganisms

How is the number of bacteria in a population after a certain time calculated from the mean division time?

A

Number of bacteria in population at the end of time period= number of bacteria in population at the beginning of time period X 2^number of divisions in time period