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Cell biology Flashcards

1
Q

What is the difference between eukaryotic and prokaryotic cells?

A

Eukaryotic cells are complex and have a nucleus
Prokaryotic cells are simpler and smaller

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2
Q

What is a eukaryote?

A

An organism made up of eukaryotic cells

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3
Q

Name all the organelles in an animal cell

there are 5

A

1. Nucleus
2. Cytoplasm
3. Cell membrane
4. Ribosomes
5. Mitochondria

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4
Q

Name all the extra organelles in a plant cell

not including those in an animal cell

A

1. Cell wall
2. Permanent vacuole
3. Chloroplasts
4. + those in an animal cell

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5
Q

What is a prokaryote and an example

A

It is a prokaryotic cell (single-celled organism)
Example: bacteria

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6
Q

Name the organelles in a bacterial cell

A

1. Cytoplasm
2. Cell membrane
3. Cell wall
4. Plasmids
5. Single strand of DNA

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7
Q

Name the 2 types of microscopes

A

Light microscopes
Electron Microscopes

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8
Q

How do electron microscopes work? What do they let us see?

A

They use electrons to form an image. They have much higher magnification and resolution.
They let us see smaller things in more detail (e.g. internal structure of mitochondria)

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9
Q

How do light microscopes work? What can they let us see?

A

They use light and lenses to form an image of a specimen and magnify it.
They let us see individual cells and large subcellular structures (e.g. nuclei)

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10
Q

What is the formula for magnification?

A

magnification = image size / real size

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11
Q

How do you prepare a slide for onion cells?

A
  1. Add a drop of water to the middle of a clean slide
  2. Cut up an onion + seperate its layers. Use tweezers to peel off some epidermal tissue from the bottom of one of the layers
  3. Using the tweezers, place the epidermal tissue into the water on the slide
  4. Add a drop of iodine solution (a stain) which will highlight the object
  5. Place a cover slip on top. Try to avoid air bubbles - they’ll obstruct the view.
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12
Q

How do you use a light microscope to observe a slide?

A
  1. Clip the slide onto the stage
  2. Select the lowest-powered objective lens
  3. Adjust mirror and turn on the light
  4. Use the coarse adjustment knob to move the stage up to just below the objective lens
  5. Slide must not touch lens
  6. Look down eyepiece. Use coarse adjustment knob to move stage downwards until the image is roughly in focus
  7. Adjust focus with fine adjustment knob, until you get a clear image,
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13
Q

How do you work out the total visual magnification from a microscope?

A

magnification of objective lens x magnification of eyepiece = total visual magnification

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14
Q

Define differentiation

A

the process by which a cell changes to become specialised for its job

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15
Q

Can cells always differentiate?

A

most animal cells lose the ability at an early stage
most plant cells retain the ability to differentiate throughout their life

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16
Q

What is an undifferentiated cell called?

A

stem cell

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17
Q

Name 5/6 specialised cells and what they’re specialised for

A

sperm cells - reproduction
nerve cells - rapid signalling
muscle cells - contraction
root hair cell - absorbing water + minerals
phloem + xylem cells - transporting substances

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18
Q

How is a sperm cell specialised?

A

lots of mitrochondria - provides energy from glucose
flagella + streamline head - mobility + movement
enzymes - digest through egg cell membrane
nucleus - contains DNA of father

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19
Q

How is a nerve cell specialised?

A

many endings - to connect with other adjacent nerve cells
myelin sheath - insulating cover
axon - (the extension of a nerve cell along which electrical impulses travel) to cover more distance

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20
Q

How is a muscle cell specialised?

A

lots of mitochondria - to generate energy for muscle contractions
(protein filaments - to determine shape and movement)

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21
Q

How is a root hair cell specialised?

A

Small thin extension - to increase surface area or root allowing plant to absorb more water + minerals from soil

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22
Q

How is a xylem cell specialised?

A

long cells and joined end to end - to form the xylem tube
hollow - so water can flow through

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23
Q

How is a phloem cell specialised?

A

long cells and joined end to end - to form the tube
few subcellular structure - so food substances (mainly sugars) can flow through

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24
Q

Where is genetic material found?

A

In the nucleus, in the form of a chromosome

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25
Define **chromosome**
coiled up **strands** of **DNA** containing large numbers of **genes**
26
Define **haploid cell/nucleus**
A **cell** or **nucleus** of a gamete that has **unpaired** sets of **chromosomes** | they only have 23 single chromosomes not 23 pairs
27
Define **diploid cell/nucleus**
A **cell** or **nucleus** that has a **paired** set of chromosomes
28
Define **gene**
a **section** of a **chromosome** made from **DNA** that carries the **code** to make **proteins**
29
Define **allele**
**two versions** of the **same gene** one from mother, one from father
30
How many **chromosomes** are there in a **human** cell?
46 - 23 pairs
31
What do multicellular organisms use **mitosis** for?
to **grow** or **replace cells** that have been **damaged**
32
What are the **steps** for **mitosis**?
1. Chromosomes **duplicate** 2. The chromosomes **line up** and the duplicates are then **pulled apart** to the **opposite ends** of the cell 3. Two **new nuclei form** because membrane forms around the chromosomes 4. The **cytoplasm** and **cell membrane divide** to form **two cells** 5. Two identical daughter cells form with **identical chromosomes**
33
What happens in stage 1 - **before** mitosis?
* The **chromosomes duplicate** * **Increase** in amount of **subcellular structures** * cell **growth**
34
What happens in stage 2 - **during** mitosis?
* **two nuclei** form * **chromosomes** pulled to **each end** of cell
35
What happens in stage 3 - **after** mitosis?
* two **identical cells form** * **cytoplasm** / membrane **divides**
36
Define **stem cells**
an **undifferentiated** cell that can **develop** into one or more types of **specialised** cell
37
Where can **stem** cells be **found** in humans? What cells can they turn into?
* in early **human embryos** (can turn into **any cell** in the body) * in **bone marrow** (can only turn into **certain cells** e.g. blood cells)
38
How can **bone marrow** **cure disease**?
**stem** **cells** from a healthy person's **bone marrow** can **replace** faulty **blood cells** in the patient
39
How can **embryonic** stem cells **cure disease**? + example
embryonic stem cells can **replace faulty cells** e.g. making **insulin-producing** cells for type 1 **diabetic** people e.g. **nerve cells** for people **paralysed** by spinal injuries
40
What is a **pro** of **therapeutic cloning**?
the cell **wouldn't be rejected** by the patients body because the **embryo** would have the **same genetic information** as patient meaning **stem cells** produced contain the **same genes**
41
What is are the **risks** of using stem cells?
* stem cells grown in a lab may become **contaminated** with a **virus** which could be **passed on** * they could be **rejected** by the patient's body (they would need to use immunosuppressant drug) * chance of **tumor forming** due to rapid divison
42
Why are some people **against** stem cell research?
They believe that human embryos **shouldn't** be experimented on because they're a potential **human life**
43
What are reasons **for** stem cell research?
* curing **existing patients** who are suffering is **more important** than the rights of embryos * embryos are usually from **fertility clinics** and would've probably been **destroyed anyway**
44
Define **meristem**
an area of a **plant** in which **rapid cell division** occurs - normally in the **tip** of the **root** or **shoot**
45
Where are **stem cells** found in **plants**?
in the **meristem**
46
What can **stem cells**, from plants, **do**?
* produce **clones** of whole plants **quickly** and **cheaply** * grow crops of **identical** plants that have **desired features** (e.g. disease resistant) * **differentiate** into **any** type of plant for their whole life * used to grow more plants of **rare species**
47
Define **diffusion**
the **net movement** of **particles** from an area of **high concentration** to an area of **low concentration** until equilibrium is reached
48
What **increases** the **rate of diffusion**?
* **high** temperatures (because there is more energy) * **bigger** concentration **gradients**
49
When a gas moves **down** the **concentration gradient**, does it move from high to low or low to high?
from **high** to **low**
50
How do **dissolved substances** move **in** and **out** of **cells**?
through the **cell membrane** via **diffusion**
50
Can **starch and proteins** diffuse through the cell membrane?
**no**, only **small** molecules
51
What does a **large surface area** of the membrane increase?
increases the **rate of diffusion**
52
Define **osmosis**
the net diffusion of **water molecules** from an area of **higher** water concentration to an area of **lower** water concentration across a **partially permeable membrane**
53
Define **partially permeable**
allowing only substances of **certain size** through
54
Do **strong sugar solutions** get more or less **dilute** during osmosis? | Is it up or down the concentration gradient?
**more dilute** because it has **fewer water molecules** | Down
55
How do you **observe** the effect of **sugar solutions** on **plant tissue**? | osmosis practical
1. Peel a **potato** and cut it into 3 **identical** cylinders (using a *cork borer*) or rectangles - each 3cm in length 2. Place **test tubes** with the different **sugar solutions**: **0.5** mol/dm^3, **0.25** mol/dm^3, **distilled** **water** 3. Weigh the **mass** of each potato and place into a test tube for **24 hrs** 4. Take them out and **dry** with a **paper towel** 5. Measure **mass** and **length** 5. The **highest** sugar solution should **shrink** the potato and the **distilled water** should have **expanded** the potato
56
Define **active transport**
the movement of **particles** from an area of **low concentration** to an area of **high concentration** using **energy**
57
Is active transport a **passive** process?
**No**, it requires energy. *Diffusion* and *osmosis* are passive processes
58
Where does the **energy** for **active transport** come **from**?
From **respiration**
59
Where does **active transport** take place in a **plant**? Why?
The **root hair** cells - the concentration of **minerals** is usually **higher in the plant** than the **soil**
60
Where does **active transport** take place in a **human**? Why?
In the **small** **intestine**/**gut** When there is a **lower concentration** of **nutrients** in the **gut** than the **blood**. Allowing **glucose** and amino acids to be **transported** to cells.
61
How are your **lungs/alevoli adapted** for **gas exchange**?
* large **surface area** * having **moist membranes** allowing substances to diffuse across them * having **thin walls** * having **rich blood supply** * **breathing** - providing a **regular supply** of fresh air
62
How is your **small intestine adapted** for **absorption of glucose**?
* they have **villi** which increase **surface area** * the *villi* have **thin walls** * they have a good **blood supply**
63
How is a **gill** **adapted** for **gas exchange**?
* has a large **surface area** due to **gill filaments** which are also covered in **lamellae** * **lamallae** have lots of **blood capillaries** * they have **thin surface layer** * **blood** flows in *one direction* whilst the **water** flows in *the opposite* - maintains a **large concentration gradient**

biology (4 decks)

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