Unit 4 - Cell Division Flashcards

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1
Q

What are induction and deduction?

A

Induction is when a conclusion is made from observations.
Deduction is when a conclusion is made from accepted facts.

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2
Q

What is a hypothesis?

A

An assumption based on limited evidence.

It must be falsefiable: meaning it can be tested.

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3
Q

What is a theory?

A

A proposed explanation based on evidence.

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4
Q

What are the three components of cell theory?

A

Cells are the basic unit of life, they are the smallest living thing.

All organisms are made up of one or more cells.

All cells come from pre-existing cells.

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5
Q

Describe Redi’s experiment that disprooved spontaneous generation.

A

Redi showed that maggots did not spontaneously generate from meat.

He did so by putting meat in a semi-closed container, showing that even if air could still pass, maggots did not generate from the meat.

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6
Q

Describe Pasteur’s experiment to disproove spontaneous generation.

A

Pasteur proved that if broth was sterilized, that is, the micro-organisms present in it were removed, then new micro-organisms would not generate.

This experiment involved boiling broth and putting it in two different swan-necked flasks.

The flask with a broken neck has its broth exposed to germ-filled air, and so micro-organisms are generated.

The flask with the intact neck is not exposed to the germs in the air, no micro-organisms generate.

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7
Q

What is the difference between the control treatment and the experimental treatment?

A

The experimental treatment or group receives the treatment that the scientists wish to study. In the case of Pasteur’s broth, it is the sterilized broth.

The control group does not receive the treatment, in this case, it is the un-sterilized broth.

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8
Q

What are the controlled variables?

A

Apart from the effect we want to isolate, nothing else is changed between the two experiments. This guarantees that no other outside factor could have affected the results.

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9
Q

What are the dependent and independent variables?

A

They are self explanatory. In the case of Pasteur’s experiment, the bacteria having or not having access to the broth is the independent variable, while the broth staying good or going bad is dependent on the independent variable.

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10
Q

What is repeatability?

A

The process is written down so that others can perform the experiment and see the results for themselves. This ensures transparency.

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11
Q

What are the steps of the scientific method?

A
  1. Make observations,
  2. Ask critical questions,
  3. Form hypothesis,
  4. Make a prediction to test the hypothesis,
  5. Experiment,
  6. Go back to step 2 if needed, adjust hypothesis,
  7. Record results,
  8. Form a conclusion,
  9. Convince peers.
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12
Q

How do we think the first cell came to be?

What were early forms of life based on?

A

Conditions on early earth are believed to have allowed the formation of amino acids and hydrocarbons.

The early forms of life were probably based on RNA, as it can self assemble, self replicate, transfer energy and catalyze reactions.

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13
Q

What are the 7 properties of life?

A

Cellular (3 components of cell theory)

Ordered complexity

Sensitivity

Growth and reproduction

Energy utilisation

Homeostasis

Evolution.

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14
Q

What is organized complexity?

A

Under a microscope, the live can be distinguished from the dead by observing ordered complexity.

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15
Q

What is energy utilisation?

A

Energy is required to power the chemical reactions necessary for life. Energy can be absorbed from food (heterotrophic), the sun (photoautotrophic), chemicals (chemoautotrophic).

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16
Q

What is homeostasis?

A

The exchange of energy and matter and waste in our body. This allows a certain regulation where organisms can make their own conditions.

An example is how our bodies are currently adjusting our inner temperature. If the outdoor temperature is 50 degrees, we do not become 50 degrees. Our body sweats when too hot, and shivers when too cold.

17
Q

What is a positive feedback loop?

What are the two possible outcomes?

A

A positive feedback loop occurs in a situation of emergency (Childbirth example).

This is when a feedback causes a change that induces more of that feedback that induces more of the change, etc.

The two possible outcomes are resolution of the emergency or death.

18
Q

How do bacteria divide?

What are the steps?

A

Bacterial division is called binary fission.

First, the circular molecule of DNA is replicated, making two molecules each containing one new strand and one old strand.

Second, the DNA molecules move towards the extremeties of the cell, which elongates and splits into two.

These two cells are called daughter cells.

19
Q

What is a karyotype?

A

A picture of a set of chromosomes organized in matching pairs.

20
Q

What holds together sister chromatids?

A

The centromere.

21
Q

What is the first phase of the cell cycle, describe its sub-phases and what happens.

A

The first phase is interphase.

This phase contains G (Gap)1, where the cell grows and is metabolically active, G0, where cells are actually working their functions, S, where DNA is synthesized and chromosomes are duplicated, and G2, where the cell prepares for division.

During G2, the centrosome, mitochondria and chloroplasts duplicate.

22
Q

What is the second phase of the cell cycle? What are its sub-phases and what happens?

A

The second phase is the M-phase, and is broken down like so:

Prophase: Chromosomes condense, Nucleus breaks down, We can start to see chromosones, Centrosomes migrate to opposite poles, Spindle fibers are formed.

Metaphase: Chromosomes are pulled by spindle fibers onto the metaphase plate at the equator.

Anaphase: Centromere break down, Sister chromatids are pulled apart.

Telophase: Spindle fibers are disassembled, ER and Golgi reappear and the Nucleus reforms. Nucleoli reappear.

Cytokinesis: Cell divides into two, Cell plate forms in plant cell

23
Q

What is aster?

A

During mitosis, the centrosomes from microtubule fibers to attach themselves to the extremeties of the cells. These fibers are called aster.

This only occurs in animal cells.

24
Q

What is a chromosome?

A

A chromosome consists of up to 1m of DNA wrapped up around a proteins called histones.

Chromosomes are tightly packed packages of DNA. They are circular in bacteria and linear in Eukaryotes.

25
Q

What is chromatin?

A

Chromatin is a substance inside the chromosome that consists of DNA and proteins such as histone.