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Science for shegs > Life at cellular level > Flashcards

Life at cellular level Flashcards

Mainly A level chemistry and biology so Ive missed tons out

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1
Q

For a spontaneous reaction to occur, what must happen?

A

Energy must be released

and/or

Entropy must increase

(Free energy change, G, must be negative)

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2
Q

For thermodynamically unfavourable reactions to occur in the body, what does the body do?

A

Reaction coupling with a catabolic reaction

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3
Q

What is metabolism?

A

The chemical processes in a living organism by which food is used for tissue growth and/or energy production

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4
Q

In terms of free energy, why is ATP used?

A

ATP hydrolysis releases free energy

Used to drive energetically unfavourable reactions

Stores free energy from exergonic reactions

(ATP hydrolysis is a catabolic process)

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5
Q

NAD, FAD and NADP are commonly used in what type of reactions?

A

Redox

They are electron carriers

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6
Q

In terms of entropy, why do lipids ‘clump together’ when in solution?

A

Increase entropy

  • H2O molecules organise themselves around hydrophobic tails ∴ ordered
  • When clumped together, total surface area of lipid decreases therefore area of ordered H2O is less therefore higher entropy
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7
Q

What is an amphipathic molecule?

A

One with both hydrophobic and hydrophilic parts

Eg phospholipids

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8
Q

Why are buffers so important to us?

A

Maintain homeostasis of pH

Enzymes and proteins structure reliant on pH

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9
Q

What is the main buffer found in blood?

A

HCO3-

bicarbonate

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10
Q

What is the first law of thermodynamics?

A

total energy of an isolated system is constant;

energy can be transformed from one form to another, but can be neither created nor destroyed

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11
Q

What is the second law of thermodynamics?

A

the total entropy of an isolated system can never decrease over time

TE can be constant if:

  • System is in steady state
  • or is undergoing a reversible process
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12
Q

Entropy of a system increases when…

A

Usable energy decreases

and un-usable energy increases

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13
Q

Organisms carry out many chemical reactions in their cells, that grow and maintain order…

How is the 2nd law of thermodynamics still obeyed then?

A

Chemical reactions increase order

This decreases entropy

But generally, heat is generated and released into the surroundings and disorders it…

Thus TOTAL entropy increases, despite entropy being decreased/maintained in cells (as 2nd law states)

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14
Q

What is anabolism?

A

the synthesis of complex molecules in living organisms from simpler ones together with the storage of energy; constructive metabolism

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15
Q

What is dynamic steady state?

A

In the process of metabolising molecule X to intermediate Y then to product Z:

If the rate of X - Y and Y - Z is equal, then the concentration of Y remains constant

This is steady state, as all the shit remains constant, and is useful in the body as it means we can have a small amount of intermediates present, compared with the number of reactions that take place

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16
Q

What is catabolism?

A

the set of metabolic pathways that breaks down molecules into smaller units that are either oxidized to release energy or used in other anabolic reactions (storage)

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17
Q

Describe how anabolism and catabolism are interdependent.

A

Free energy flows between catabolic and anabolic pathways/reactions

Allowing them to occur

18
Q

ATP hydrolysis is used to supply energy to make ______ happen

A

Energetically unfavourable reactions

19
Q

What type of reaction is ATP often ‘made’ in?

catabolic or anabolic?

A

Catabolic
(Breakdown of complex to simple molecules)

Releases energy which is used to Phosphorylate ADP to make ATP which carries the energy to an anabolic reaction to allow it to happen (simply)

20
Q

Example

When PEP undergoes reactions to form pyruvate, what is the involvement of ADP/ATP?

A

ADP phosphorylated to ATP

PEP > Pyruvate is catabolic thus releases energy

Stored in ATP

21
Q

ATP hydrolysis is an ______ reaction

A

Exergonic

decrease in free energy

22
Q

What are the 5 chemical reaction types of life?

OGBIC

A
  • Oxidation / reduction
  • Group transfers
  • Bond making / breaking
  • Internal rearrangements
  • Condensation and hydrolysis
23
Q

What type of chemical reaction is NAD+ and NADH involved with?

A

Redox

24
Q

What is the difference between substrate level and oxidative phosphorylation?

A

Substrate-level phosphorylation is directly phosphorylating ADP with a phosphate and energy provided from a coupled reaction

Oxidative phosphorylation is when ATP is generated from the oxidation of NADH and FADH2 and the subsequent transfer of electrons and pumping of protons (electron transport chain)

(If you don’t know what oxidative p. is, dont worry, its in terminal respiration lectures)

25
Q

Describe the structure and role of the nucleus.

A 
Nuclear envelope - double membrane 
Nuclear pores 
Nucleolus 
Chromatin 
Nucleoplasm

Stores DNA and coordinates cellular activity

26
Q

Highlight the structure and function of the endoplasmic reticulum

A

SER and RER

  • Interconnected membrane tubes
  • Synthesis, storage and transport of biomolecules

RER - protein synthesis at ribosomes attached to surface

SER - Fatty acids, steroids, lipids (phospholipids made here and steroid hormones made from cholesterol)

27
Q

What is the structure and function of mitochondria?

A 
Double membrane 
Cristae 
Mitochondrial matrix (enzymes, ribosomes, granules etc)
Small amount of own DNA 
Cristae

ATP synthesis - aerobic respiration (oxidative phosphorylation)

28
Q

Describe what the Golgi is/does…

A

Series of hollow sacs (cisternae)
Surrounded by/produces vesicles

Receives and modifies proteins
Then packages them into vesicles for transport

29
Q

Describe the different types of vesicles found in cells…

A

Secretory and storage

Secretory - contain proteins to be released from the cell via exocytosis

Storage - Store stuff

30
Q

Describe what lysosomes and peroxisomes are.

A

Lysosomes - type of storage vesicle. Breaks down unwanted stuff in the cell using powerful enzymes

Peroxisomes - also a type of storage vesicle. Smaller than lysosomes. Involved with break-down of long chain fatty acids (in lipid metabolism lectures)

31
Q

What are cilia and flagella? How are they similar/different?

A

Cilia

  • hair like structures on some cells in the body such as the cells lining the airways
  • sweep secretions and particles across the cells
  • made of microtubules
  • single cilia are sensors

Flagella

  • also made of microtubules but are longer than cilia
  • free-floating cells (eg sperm)
  • wave like movements used for propulsion of cell

Cells with cilia are fixed and move other stuff, whereas cells with flagella use them for their own movement

32
Q

What is the cell cytoskeleton?

A

Flexible scaffolding that spans across the cytoplasm of cells

Made of:

  • actin filaments
  • intermediate filaments
  • microtubules
33
Q

What are the main roles of the cell cytoskeleton?

A

Cell shape

Hold position of organelles - organisation

Intracellular transport - acts a bit like a railway network

Connects to extracellular protein fibres - incorporating the cells into tissues

Movement of cells - eg it is used when WBC’s squeeze out of blood vessels to fight infection

34
Q

What is the general rule about solubility in water and in lipids and charge?

A

Polar/charged = soluble in water

Un-charged/un-polar = soluble in fat

35
Q

What does amphipathic mean, and what is an example of an amphipathic molecule?

A

Molecule having both hydrophilic and hydrophobic parts

phospholipids

36
Q

Define what pH is.

A

Negative logarithmic scale of proton concentration in a liquid, showing how acidic or alkaline a substance is

37
Q

What is the equation for pH?

A

-log10[H+]

log10 = log to the base 10

38
Q

What is the difference between a weak acid and a strong acid?

A

Strong - fully dissociates in solution

Weak - only partially dissociates

39
Q

What is the ionic product of water, and what is it useful for finding?

A

1 x 10^-14

Used to find the pH of an alkaline substance

[H+] = (1 x 10^-14) / [OH-]

40
Q

What is a buffer and why are they fundamental to human life?

A

Solution that resists changes in pH when small additions of acid or alkali are made

Needed in our blood especially in order to maintain homeostasis

Our blood must be a specific pH otherwise we would die,
pH affects protein shape and function, for example

Science for shegs (28 decks)

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