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Biology 3/4 > Holiday homework/cell/protein synthesis > Flashcards

Holiday homework/cell/protein synthesis Flashcards

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1
Q

What is exocytosis and its process?

A
  • active movement of substances outside the cell in membrane-bound vesicles
  1. Vesicles form inside the cell from the RER, golgi apparatus, lysosomes and endosomes
  2. Vesicles containing newly synthesised proteins or waste products move towards the plasma membrane
  3. plasma membrane and vesicular membrane fuse together
  4. contents of vesicle expelled into extracellular fluid
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2
Q

What are cells?

A
  • the basic structural and functional unit of life
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3
Q

Why do cells need to be small?

A
  • maximise their surface area to volume ration to efficiently move ions, nutrients and waste
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4
Q

Prokaryotes vs eukaryotes:

A

Prokaryotes: bacteria and archaea
- lack membrane boune nucleus
- unicellular
- no cytoskeleton
- chemicallu complex cell wall
Eukaryotes: animals, plants, chromista, fungi, protozoa,
- mostly mutlicellular (can be unicellular)
- sometimes cell wall but chemically simple

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5
Q

Importance of compartmentalisation in eukaryotic cells:

A
  • efficiency
  • creates specific microenvironments (e.g. pH, ion concentration) within the cell so each organelle can have the advantages it needs to perform to the best of its ability
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6
Q

Location of nucleolus and what it does

A
  • within nucleus
  • ribosomal subunits are synthesised
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7
Q

Where can ribosomes be found and what is their role?

A
  • free in cytosol or attached to RER
  • role is protein synthesis
  • small subunit reads mRNA and large subunit joins amino acids which are connected via peptide bonds to form polypeptide chains
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8
Q

what do the endoplasmic reticulums look like?

A
  • interconnected network of flattened membrane-enclosed channels
  • continuous with outer nuclear membrane
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9
Q

Role of smooth ER

A
  • synthesise lipids
  • metabolism of carbohydrates
  • calcium storage
  • detoxification of drugs and poisons
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10
Q

Role of rough ER and what happens to proteins there

A
  • processes proteins from ribosomes
  • attaches sugar groups to some proteins to form glycoproteins
  • folds proteins into correct functional shape
  • joins together several popypeptide chains to form complex proteins
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11
Q

Golgi apparatus appearance and function

A
  • mutli layered structure composed of stacks of membrane-lined channels with wider ends
  • modifies, sorts, packages and distributes proteins into secretory vesicles
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12
Q

Lysosomes

A
  • membrane bound sac
  • found only in animal cells
  • contains digestive enzymes
  • breaks down material taken into the cell and obsolete components of the cell itself
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13
Q

Vacuoles

A
  • large membrane bound vesicles
  • only in PLANT cells
  • maintain water balance
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14
Q

peroxisomes

A
  • lipid metabolism
  • breaking down harmful hydrogen peroxide into water and oxygen
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15
Q

mitochondria

A
  • double membrane
  • inner membrane has series of folds (cristae) containing enzymes for ATP synthesis
  • matrix is fluid-filled space within inner membrane
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16
Q

Plasma membrane

A
  • semi permeable
  • controls the entry and exit of materials into and out of cells

Functions:
- is an active and selective boundary (separates cell from external environment)
- denotes cell identity (vital for immune response)
- receives external signals
- transports materials.

17
Q

Factors that affect a substance’s ability to cross a membrane

A

Molecules that can pass easily through the cell membrane:
* small polar molecules such as water
* non-polar molecules such as carbon dioxide.
Molecules that cannot pass easily through a membrane:
* large polar molecules such as glucose
* charged molecules.

18
Q

Simple diffusion

A

the movement of solute particles across a semi-permeable membrane from a region of high concentration to a region of low concentration to reach equilibrium

  • small polar molecules
  • non-polar (lipophilic/hydrophobic)
19
Q

Facilitated diffusion

A

involves protein transporters and is the means of transport
of dissolved hydrophilic substances
- high to low concentration
- large polar and charged molecules

20
Q

Active transport

A

net movement of
dissolved substances across a cell
membrane by an energy-requiring
process that moves substances
against a concentration gradient
from a region of lower to higher
concentration

  • hydrophyllic substances
21
Q

Bulk transport

A
  • active transport
  • too large for carrier proteins
  • high to low concentration

Endocytosis:
- enter cell
- phagocytosis (solid)
- pinocytosis (liquid)
1. substance approaches plasma membrane
2. Portion of plasma membrane is invaginated
3. membrane forms vesicle that contains substance

Exocytosis:
- substance encolsed in a vesicle from the golgi apparatus
- vesicle fuses with plasma membrane and releases contents

22
Q

Osmosis

A

a specialised process of
passive transport in which water
molecules move across a partially
permeable membrane from an area
of high water (low solute) to an area
of low water (high solute)

23
Q

structure of membrane

A
  • double layer of phospholipids
    (hydrophilic heads on outside, hydrophobic tails face each other)
  • fibrous proteins (receptors)
  • pore proteins (allow water molecules to pass through)
  • channel proteins (ions)
  • cholestoral (animal cells only)
  • at low temps, maintains fluidity by keeping phospholipids separated and keeping it from becoming too stiff
  • at high temps, stabilizes membrane by raising melting point and preventing it from becoming too fluid
    reduces permeability to some small water-soluble molecules
  • carbohydrates: attached to lipids (glycolipid), attached to proteins (glycoproteins) (peripheral)
    identification and recognition
24
Q

How to describe structure of plasma membrane

A
  • fluid mosaic model
  • phospholipids can move laterally (influenced by unsaturated fatty acids- kinks in the tail that make it more fluid)
  • looks like a mosaic with proteins embedded
25
Q

Phospholipids

A
  • two fatty acid chains (non polar/hydrophobic)
  • joined to phosphate containing group (hyrdophilic/polar)
26
Q

Proteins in membrane

A

Integral proteins:
permanent parts of cell membrane

Transmembrane proteins:
span both phospholipid bilayers

Peripheral proteins:
- temporary
- surface of membrane

27
Q

Coded vs decoded information

A

Coded information: nucleotide sequences in DNA template strand

Decoded information: order of amino acids in a polypeptide (sequences are read and traslated into proteins)

28
Q

why is the genetic code referred to a triplet code?

A

the idea that the
genetic code consists of triplets
or three-base sequences

29
Q

what is the strand of a DNA
double helix that is complementary
to the template strand

A

the coding strand, non-template strand

30
Q

what is pre-mRNA also known as?

A

the primary transcript

31
Q

what is tRNA made out of?

A
  • single strand of 76 nucleotides coiled and paired with themselves
  • anticodon
  • region that attaches to one specific amino acid
  • amino acyl tRNA synthetase catalyses linking of amino acid with tRNA
32
Q

what are the advantages and disadvantages of the universability of the genetic code in humans?

A

Advantages:
- gene manipulation and therapeutic uses: can insert human genes into any other organism such as bacteria and they can express the same proteins as in humans.
e.g. insulin
- more easily sequence genes of other species and determine the proteins that will be produced

Disadvantage:
- easier for foreign dna to be incorporated into a genome. e.g. some viruses can hide in the genomes of host cells without being recognised as foreign

33
Q

A change in the DNA sequence that does not result in a change in the amino acid sequence is known as a ??? mutation.

A

silent

34
Q

What would be the consequence if the fifth-last base in the sequence mutated from adenine to thymine, changing the stop protein to another amino acid?

A

It would change the length of the polypeptide, possibly chaning structure and function of the protein.

35
Q

how many amino acids can humans not make?

A

9 (histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan and valine.)

Biology 3/4 (2 decks)

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