4 Flashcards

1
Q

Why is the plasma membrane a phospholipid bilayer

A

phosphlipid bilayer is composed of hydrophilic head which faces outwards to form the bilayer BECAUSE they attract water and hydrophiobic tails which face inwards away from the intra nad extracelluar fluid because they repel water

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2
Q

Why are so many cells needed

A

to exchange more materials and for better survival of the cell

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2
Q

Fluid mosaic model

A

A model that describes the structure of cell membranes

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3
Q

what is constantly moving in the fluid mosaic model

A

phospholipids, sterols and proteins

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3
Q

Difference between hydrophilic head and hydrophobic tail

A

hydrophilic head-attracted to water
hydrophobic tail-repels water

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4
Q

what is the cell memrbane structured as

A

phospholipid bilayer

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5
Q

what is the head and tail of the fluid mosaic model composed of

A

head is made of hydrophilic phosphate
the tail is made of hydrophobic fatty acid

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5
Q

what can fatty acids be in phospholipids

A

be saturated (form straight chains) or unsaturated (kinked chains)

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6
Q

Why is it called the fluid mosaic model

A

phospholipids are constantly moving around like a liquid, hence the term fluid

The phospholipids, proteins, and cholesterol and the other substances that make the lipid bilayer create a mosaic like pattern hence, the term mosiacc

Therefore, it is known as the term fluid mosiac model

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7
Q

some proteins are bound onto the membrane surface whilst others are…

A

embedded in the phospholipid bilayer

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8
Q

Receptor protein

A

protein molecule that has receptor sites at the end of carb chains that bind with ligands to trigger a series of chemical reactions

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9
Q

ligands

A

specific signal molecules eg. lips, ions and carbohydrates

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10
Q

Transport proteins

A

Allows speficifc substances to move across a membrane eg. channel and carrier proteins

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11
Q

Extracellular fluid

A

liquid that supplies nutrients and removes waste found on the outside of cell memrbaen

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12
Q

factors that effect the permeability of the membrane

A

heat
PH
ethanol

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13
Q

how does heat, PH and ethanol effect the permeability of cell membrane

A

high temperatures and change in PH levels cause proteins to denature, hecneincreasing permeability

the permeability of the cell membrane also increases when ethanol dissolves lipid components of the membrane which creates holes in the membrane

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14
Q

what do kinked chains do

A

prevent the phospholipids from being stacked together hence, increasing and maintaining fluidity even in cold climates

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15
Q

what organelles are composed of a phosplipid bilayer

A

cell membrane and vesicle

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15
Q

why does the cell membrane get larger when a vesicle is added

A

both organelles are made up of a phopslipid bilayer which means when these 2 organelles fuse, the cell membrane becomes larger

16
Q

what is the process of translation

A

mRNA is read by ribosomes to create a polypeptide chain of amino acids (protein)

16
Q

what do receptor sites do

A

receive signals

17
Q

Messenger rna

A

a copy of DNA that carries out instructions to ribosomes for translations

18
Q

Transfer rna

A

carries a specific amino acid to the ribosome for translation

18
Q

surface protein

A

proteins that are attached to the surface of the membrane that play a role in cell communication

19
Transmembrane proteins
proteins that are embedded in the phospholipid bilayer that only allow specific substances across the membrane
20
Integral proteins
protein that is permanently attached to the cell membrane membrane
21
Peripheral proteins
temparoolty attached to the cell membrane
22
4 main types of proteins in cell membrane
Surface proteins – Transmembrane proteins Integral proteins Peripheral proteins
23
Types of transmembrane proteins
Receptor protein Transport proteins
24
each receptor-ligand pair bind with a lock-and-key fit- to do what?
to allow receptor proteins to become either activated or inactivated leading to an intercellular response
25
WHAT IS THE LOCK AND KEY MODEL?
the lock and key model explains that the ligand (signalling molecule) is shaped complementarily to the receptor protein so that they can fit in each other. The ligand acts as a key whilst the receptor acts a lock and this binding causes a celluar response
26
what does the lock and key model result in
causes the receptor protein to either become activated or deactivated creating a response inside the cell.
27
channel protein
type of transport protein that causes ions and water to flow through cell membrane
28
examples of polar substances and whether they are hydrophilic or hydrophobic
water and ions hydrophilic
29
what do non non polar substances attract and whether they are hydropholic or hydrophobic
eg, fats hydrophobic
30
what diffuses through the cell membrane easily and why
Small non-polar substances because non polar substances attract fat and the cell membrane is made of fat, Also, Small hydrophobic substances because they repel water and attract fat as well.
31
what else besides polar substances are unable to cross through the cell membrane
Really large substances eg. glucose
32
in what form is the genetic material found
chromatin
33
areboic respiration
the exchange of oxygen and carbon dioxide
34
carrier proteins
A type of transport protein that allows water and ions to flow through the membrane. However, unlike a channel protein when a substance enters one side of the carrier protein closes and another opens continuously.
35
what is the cell membrane made of
lipids such as phospholipids and proteins
36
What is the plasma membrane
a secelectvitley permable membrane that controls the movement of substances, in and out of the cell.
37
Transcription
Dna is replicated into an mRNA
38
difference between transcription and translation
transcription occurs first- a copy of DNA is made(mRNA) Translation: occurs after transcription mRNA is read by ribosomes to create proteins
39
what factors increase perambilty
steeper concentration graident higher temperatures PH