2A & 3A Cells and Transport Flashcards
(66 cards)
1
Q
name 3 similarities and 3 differences between prokaryotic and eukaryotic cells
A
similarities:
- both have ribosomes
- both have cell surface (plasma) membranes
- both have cytoplasm
differences:
- prokaryotic DNA in plasmids and cytoplasm whereas eukaryotic DNA in nucleus
- eukaryotes have membrane-bound organelles whereas prokaryotes do not
- eukaryotes are larger
- prokaryotes have plasmids
2
Q
magnification
A
size of image / size of real object
3
Q
tissue
A
- group of similar cells
- that are specially adapted
- to work together to carry out particular function
4
Q
what kind of cell does MITOSIS produce
A
genetically identical daughter cells
5
Q
what is mitosis needed for?
A
- growth
- repairing damaged tissues
- asexual reproduction
6
Q
what does the cell cycle consist of?
A
- INTERPHASE -> period of cell growth and DNA replication (G1 -> SYNTHESIS ->G2)
- MITOSIS
7
Q
what happens during INTERPHASE?
A
- G1 -> cell grows and new proteins made
- SYNTHESIS -> cell unravels and replicates its DNA ready to divide by mitosis
- G2 -> cell keeps growing and proteins needed for cell division are made
-> ATP content increased
cell’s organelles also replicated so to has spares
8
Q
order of stages in mitosis
A
P ussy like BMAT but for pussies
M edical
A dmissions
T est
- PROPHASE
- METAPHASE
- ANAPHASE
- TELOPHASE
9
Q
what happens in PROPHASE?
A
- chromosomes condense -> get shorter and fatter
- centrioles (bundles of proteins) moving to opposite ends of cell -> makes network of protein fibres = SPINDLE
- nuclear envelope breaks down and chromosomes lie free in cytoplasm
10
Q
what happens in METAPHASE?
A
- chromosomes (each with 2 chromatids) line up along middle of cell
- and become attached to spindle by centromere
11
Q
what happens in ANAPHASE?
A
- centromeres divide -> separating each pair of sister chromatids
- spindles contract -> pulling sister chromatids to opposite ends of spindle
- makes chromatids appear v-shaped
12
Q
what happens in TELOPHASE?
A
- chromatids reach opposite ends on spindle
- uncoil and become long and thin (chromosomes again!)
- nuclear envelope forms around each group of chromosomes so there are 2 nuclei
- cytoplasm divides -> now 2 genetically identical daughter cells!
13
Q
what is cholesterol?
A
component of cell membrane that allows whole thing to be fluid / rigid depending on temp
14
Q
diffusion (passive)
A
net movement of particles from area of high conc.->low. conc.
passive process -> no ATP needed
15
Q
active transport
A
movement of molecules / ions across SEMI-PERMEABLE MEMBRANE from low->high conc. using ATP and carrier proteins
16
Q
receptors
A
molecules (could be proteins) in cell membrane that recognise other molecules that can enter cell
17
Q
glycoproteins
A
act as cell receptor on surface membrane
18
Q
functions of proteins in cell membrane?
A
transport
communication
19
Q
intrinsic proteins
A
= integral
- embedded in MEMBRANE
- with PRECISE ARRANGEMENT DETERMINED by …
- their HYDROPHILIC and HYDROPHOBIC regions
20
Q
extrinsic proteins
A
= peripheral
found on the outer or inner surface of the membrane
21
Q
why is cholesterol important in cell surface membrane?
A
increases fluidity of membrane at low temp. stops it becoming too RIGID
-> as cholesterol stops phospholipid tails packing too closely together
22
Q
how does relationship between cholesterol and phospholipid tails affect cell membrane?
A
interactions stabilise cell membrane at higher temp. by stopping membrane from becoming too FLUID
23
Q
state 2 factors that affect permeability of cell membranes
A
- temp
- alcohol conc (ethanol)
24
Q
how is beetroot used to measure permeability of cell membranes?
(3 marks)
A
high permeability = more red (betalains) pigment leaks out into surrounding sol in given amount of time
colorimeter used to determine absorbance hence conc of pigment
25
outline procedure to investigate **effect of temp on permeability** of cell membrane
1. cut **beetroot** into 8 identical cubes with scalpel (no skin) -> put in **distilled water overnight** to remove any **dye** released when cut
2. wash and blot dry with filter paper
3. place each cube in 8 diff test tubes with **10cm³ distilled water**
4. place each test tube into **8 diff water baths** ranging from **0-70 ℃**. leave for **30 mins**
5. filter each sol out into cuvette and read absorbance using colorimeter
26
what are the **safety hazards** in testing effect of **ethanol** on membrane permeability?
- ethanol is an **IRRITANT** and **FLAMMABLE**
-> keep away from **naked flames** and wear goggles
- keep **sharp scalpel** away from fingers
- handle **hot water** with care
27
explain effect of temp on membrane permeabilty
(3 marks)
- **increasing** temp = increase in **membrane permeability**
-> high temp **DENATURE** some **membrane proteins**
-> creates **gaps** in **membrane** for molecules to **pass through**
- **decreasing** temp = decreases **Eᵏ of phospholipids** -> so they **pack tighter together**
-> **restricts movement** of molecules across membrane
28
what is the effect of increasing ethanol conc on membrane permeability?
increasing ethanol conc = **increased membrane permeability**
-> as ethanol **ruptures membrane** to form **gaps** for molecules to **pass through**
29
how does **low** s.a : vol ratio affect transport of molecules?
**low** s.a : vol ratio = **further distance** molecules need to travel to **reach all parts of organism**
- **diffusion** alone **isnt sufficient** so **SPECIALISED GAS EXCH. SURFACES required**
30
name 3 features of efficient gas exchange surface
- **large s.a** -> eg **folded membranes** in mitochondria
- **short** distance -> walls of **capillaries**
- **steep conc grad maintained** by **BLOOD SUPPLY / VENTILATION** eg alveoli
31
what is Ficks Law?
large s.a = larger diff in conc
shorter diffusion distance = faster rate of diffusion
rate of diffusion ∝ ( s.a x conc diff ) ÷ membrane thickness
32
where in plants can cells undergoing mitosis be found?
**meristem tissue** at shoot and root tips
33
what is the mitotic index?
ratio of
cells undergoing mitosis : total no. of cells in sample
34
outline procedure to prepare root tip slide
(abbrieviated version)
1. **warm** 2 cm³ 1M HCl to **60℃** in water bath
2. cut 1-2 cm root tip of **garlic** and **add to HCl** -> leave for **5 mins**
3. remove from HCl and **wash** with **cold distilled water**
4. dry and place on slide
5. **macarate** with **mounted needle** to **spread out cells**
6. add 1 drop **stain** to make chromosomes **visible** and observe
35
mitotic index calculation
| do q's on this
no. **cells** with **visible chromosomes**
÷
no. cells in sample
36
state hazards and precautions for reagents in observing stages of mitosis practical
**HCl** -> **corrosive**, avoid contact with skin
**Toluidine Blue O stain** -> irritant, avoid contact with skin
scalpel -> cut away from fingers
37
why is the root tip placed in hot HCl?
(stages of mitosis practical)
HCl **dissolves MIDDLE LAMELLAE** in order to **break up cellulose cell wall**
this allows **STAIN to PERMEATE** and **TIP** to be **SQUASHED** more easily
38
describe how the lungs are adapted for rapid gas exchange
- **lots of alveoli** = **larger s.a** for diffusion to occur across
- alveolar epithelium and capillary epithelium are **one cell thick** -> short diffusion pathway
- all alveoli have good **blood supply** from capillaries
-> constantly **take away O₂** and **bring more CO₂**
= **maintains** conc gradient
- breathing in and out refreshes air in alveoli -> keeps conc grad **high**
39
organ system
group of different **organs** that work together to carry out a particular function
40
osmosis
**net movement** of **free** water molecules across **partially permeable membrane** from area of **high to low conc**
41
facilitated diffusion
- diffusion of **larger molecules** (eg **glucose, a.a**) and charged particles (**ions**) via carrier / channel proteins in cell membrane
as these molecules / ions **cannot diffuse directly** through bilayer
42
endocytosis
cells taking in substances that are **too large** to be taken into cell via **carrier proteins**
- cell **surrounds substance** with section of its cell **membrane**
- membrane pinches off to form **vesicle** inside cell containing ingested substance
43
exocytosis
movement of substances leaving cell
as some substances (eg. **dig enzyme**, **hormones**, **lipids**) made by cell
- vesicles containing substances pinch off from **sacs of golgi** **apparatus** and move towards cell membrane
- vesicles **fuse** with **cell membrane** and **release** contents outside cell
44
describe how a **carrier** protein operates
move larger molecules in / out of cell
**diff** carrier proteins facilitate diffusion of **diff molecules**
1. large molecule **attaches** to carrier protein in membrane
2. protein **changes shape** ...
3. ... releasing molecule on opposite side of membrabne
45
describe how a **channel** protein operates
channel proteins form **pores in membrane** for charged particles to **diffuse** through (down conc grad)
46
which organelles in eukaryotes have double membranes?
- mitochondria
- nucleus (nuclear envelope)
- (chloroplasts) for plants only
47
describe the nucleus and its function in eukaryotic cells
- large organelle surrounded by **nuclear envelope** (double membrane) ...
- ... with **pores** (gaps) -> allow substances eg **RNA** to move from nucleus->cytoplasm
- contains **chromatin** **(made from DNA and proteins)**
- contains **nucleolus** -> makes **ribosomes**
48
describe the lysosome and its function in eukaryotic cells
round organelle surrounded by membrane
-> contains **dig enzymes** which can ...
- eat **invading** cells
- eat **worn out bits** of cell
49
where are ribosomes in eukaryotic cells and what are they made of?
- cytoplasm
- **attached to rER**
made of **proteins** and **RNA**
| **NO MEMBRANE**
50
describe the rER and its function in eukaryotic cells
- **system of membranes** enclosing fluid-filled space
- surface covered in ribosomes
- **folds** and **processes proteins** that have been made at ribosomes
51
describe the sER and its function in eukaryotic cells
- system of membranes enclosing fluid-filled space
- but NO RIBOSOMES
- **synthesises** and **processes lipids**
52
describe the Golgi apparatus and its function in eukaryotic cells
- group of fluid-filled membrane-bound, flattened sacs
- has vesicles at edges of sacs
- **processes** and **packages** **new lipids and proteins**
- **makes lysosomes**
53
describe the mitochondria and their function in eukaryotic cells
- **double membrane** with inner one folded to form **cristae**
- inside is matrix -> contains **enzymes** involved in **respiration**
- site of **aerobic** respiration -> where **ATP** produced
54
describe the centrioles and their function is eukaryotic cells
- small hollow cyclinders made of **mictrotubules** (tiny protein cyclinders)
- in all animal cells but also **some plant cells**
- involved in **separation of chromosomes** during **cell division**
55
describe how organelles in eukaryotic cells allow **protein transport** within cells
1. proteins made in ribosomes
2. ribosomes on rER make proteins that are **excreted / attached to cell membrane**
3. free ribosomes in cytoplasm make proteins that **stay in cytoplasm**
4. new proteins **made at rER** are **folded** and **processed** (eg. ***sugar chains added***) **in rER**
5. **rER packages proteins in vesicles**
6. then **transported to golgi in vesicles**
7. at golgi: proteins undergo **further processing** (eg. sugar chains trimmed / more added AND *prosthetic groups* added eg. iron in haemoglobin)
8. proteins **enter more vesicles** to be **transported around cell**
-> eg. **extracellular** enzymes (eg. dig enzymes) move to **cell surface** to be **secreted**
56
describe the DNA in prokaryotic cells
***- circular DNA:***
->one **long coiled up strand** (bacterial chromosome in bacteria cell)
-> **not attached** to any **histone proteins**
-> floats free in cytoplasm
***- plasmids:***
-> small loops of DNA
-> contains **genes** for eg. **antibiotic resistance**
-> can be passed between prokaryotes
57
describe mesosomes in prokaryotic cells
**inwards folds** in **plasma** membrane
could be used in cellular processes or just artifact in cells
58
some prokaryotes have pili. describe their function in these cells
help prokaryote **stick** to other cells
-> used in **transfer** of **genetic material** **between** cells
59
describe the function of cell wall in prokaryotic cells
**supports** cell and prevents it changing shape
made from **polymer murein** (**glycoprotein**: protein with **carb** attached)
60
describe the function of the **capsule** in prokaryotic (eg. bacterial) cells
made of **secreted slime**
helps **protect bacteria** from **attack** by **cells of immune system**
61
organ
group of **different tissues** that work together to perform a particular function
62
give one diff between a tissue and an organ
tissues made of **one type of cell**
organ made of **diff tissues**
63
active transport
- uses **ATP** to move molecules / ions from low->high conc (**against conc grad**) ...
- across plasma membranes
- using **carrier proteins**
64
active transport requires ATP.
Describe where this ATP comes from in animals
- **ATP** produced from **respiration**
- acts as **immediate source of energy** in cell
- when ATP is **hydrolysed**: broken down into **ADP + Pi** ...
- **releasing energy** ...
- which is used to move molecule against conc gradient
65
suggest what would happen if phospholipid bilayer had no cholesterol
cholesterol controls rigidy/fluidity
too fluid = unstable, cell would **burst under osmotic Pa**
too rigid = brittle
66
rate of diffusion
| using Ficks Law
**Permeability constant** x **s.a**
x (**conc difference** ÷ **thickness of membrane**)
