Cell biology

Question 1

What is a cell

Answer 1

A cell is a chemical system that is able to maintain its structure and reproduce. They are the simplest collection of matter than can live, their structure is related to their function and they all derive from stem cells.

Question 2

What are the three main principles of cell theory

Answer 2

All living things are composed of one or more cells.
The cells is the basic unit of life.
New cells arise from existing cells.

Question 3

What are the nine shapes of cells

Answer 3

Squamous
Cuboidal
Columnar
Polygonal
Stellate
Spheroid
Discoid
Spindle-shaped
Fibrous

Question 4

What are the four main tissues found in the human body

Answer 4

Connective
Nervous
Muscle
Epithelial

Question 5

Connective tissue

Answer 5

often forms joining structures in organ,

blood and bone are also considered connective tissue

Question 6

Nervous tissue

Answer 6

It is electrically active and is part of the nervous system

Question 7

Muscle tissue

Answer 7

Is further divided into skeletal, smooth and cardiac muscle

Question 8

Epithelial tissue

Answer 8

Forms linings on our organs

Question 9

How are cells studied

Answer 9

Through
microscopy - Structural information
Biochemical analysis - functional information

Question 10

Types of Microscopy

Answer 10

Light microscopy - using light waves to form the image, resolution of 200nm
magnification of 1000x

Electron microscopy - acceleration electrons to make them behave as waves rather than particles
resolution of 0.5 nm
magnification of 10.000x
(Ultra-structural images)

Question 11

Biochemical Analysis

Answer 11

Set of techniques that allow scientists to study how the different organelles operate and the interaction of molecules.

It is done by cell fractioning and homogenisation by using a centrifuge.

Question 12

What are the cell domains

Answer 12

Prokaryota ( Bacteria and Archaea)

Eukaryota

Question 13

What are the common features to all cells

Answer 13

Plasmar membrane
Semi-fluid substance - cytosol
Chromosomes - carry genetic information
Ribosomes - make proteins

Question 14

Characteristics of Prokaryotic cells

Answer 14

lack of membrane bound organelles ( nucleus, mitochondria)
Have a single DNA circular piece - NUCLEOID
their size rage is 1 to 10 muM
they are mostly monocellular organisms

Question 15

Characteristics of Prokaryotic cells

Answer 15

lack of membrane bound organelles ( nucleus, mitochondria)
Have a single DNA circular piece - NUCLEOID
They are mostly monocellular organisms
Their size ranges from 1 to 10 muM

Question 16

Characteristics of Eukaryotic cells

Answer 16

Have membrane-bound organelles
DNA is packed with in the nucleus and organised in chromosomes
Their size ranges between 10 to 100 muM

Question 17

organelles

Answer 17

Plasma membrane
Nucleous
Endoplasmatic reticulum
Golgi apparatus
mitochondria
lysosomes
ribosomes
(Cytoskeleton)

Question 18

Plasma membrane

Answer 18

It is the outer layer of the cell and it is made of a phospholipid bilayer with the hydrophilic side on the outside and inside, this solubilizes the membrane.

It has proteins, lipids and carbohydrates embebed.

It controls substances and signals into and out of cells .

Helps maintain cytoplasmic composition, cell volume.

Question 19

Nucleous

Answer 19

Has an outer membrane, the nuclear envelope, perforated with pores ( connects its with the rest of the cell.

Inside of it we found the chromatine ( genetic material `associated proteins); There is heterochromatine ( condensed and not actively used). And Euchromatin (uncoiled and used).

Inludes a nucleolus

Question 20

What is a Nucleolus

Answer 20

It is a specialised region fo the nucleous where ribosomes are produced.

Question 21

What is DNA built up from

Answer 21

Nucleotides,

Each include a nitrogenous base ( purines - 2 rings or pyrimidine, 1 ring);
A pentose sugar (Desoxyribose)
and a phosphate group

Question 22

What is the structure of DNA like

Answer 22

The molecule consists of two polynucleotide chains, bases are inside and form hydrogen bonds (weak);
and the backbone is a repetition of phosphate-deoxyribose which form covalent bonds (strong).

Question 23

Adenine pares with

Answer 23

Thymine

Question 24

Guanine pares with

Answer 24

Cytosine

Question 25

Uracil substitutes … in RNA

Answer 25

Thymine

Question 26

Endoplasmatic Reticulum

Answer 26

It is a network of sacs directly connected to the nucleous that acts as a transport system;

These sacs are continuous and interconnected in one cisternal space.

There is rough ER and smooth ER.

Question 27

Sooth ER

Answer 27

Produces molecules like steroids, other lipids and glucose. in muscle cells it specializes in CA+2 storage, in liver cells it specializes in detoxification

Question 28

Rough ER

Answer 28

Has ribosomes which are responsible for protein production

Question 29

Golgi Apparatus

Answer 29

It is a series of stacked cisternae which receives proteins from the rough ER and modifies these into the final product.

These modifications include cutting, splicing and addition of molecules like carbohydrates.

Then it packages the proteins in membrane-bounded Golgi vesicles for delivery. Then they are transported to other parts of the cell or fuse with the membrane and release the contents to the outside of the cell.

Question 30

How are proteins synthesised

Answer 30

DNA, which hold the code for generating proteins, is uncoiled and split into the coding and the template strands.

The latter is copied into the mRNA, which contains uracil instead of thymine, in a process called transcription, and exits the nucleous through the nuclear pores.

It binds with ribosomes, which read the information one codon (three bases) at the time. Each codon tells which amino acid to attach to the growing polypeptide.

The protein then folds and can be modified by the golgi apparatus and packed into vesicles for transportation.

Question 31

Mitochondria

Answer 31

The mitocondria is where part of the reaction to transform energy into ATP happens.
It has a double membrane, being the one inside very folded to increase the surface where this reaction can take place.

Question 32

Sugar into ATP

Answer 32

Energy, usually in the form of sugar has to be converted into ATP so that it can be used in other chemical reactions.

C6H12O6 + 6O2 + 6H2O –> 12H2O + 6CO2 + ATP.

The first part of the respiration of glucose takes part in the cytoplasm (glycolisis) the next two parts take place in the inner membrane (Krebs cycle oxidative phosphorylation). This is why the inner membrane is as highly folded, to have more surface area where the process can happen.

Enzymes catalyse the respiration of pyruvic acid to ATP.

Question 33

Lysosomes

Answer 33

It is a vesicle that contains digestive enzymes and has a low pH to aid the digestive and lytic process. These breaks down damaged and old organelles as well as foreign particles so they can be recycled.

Question 34

The cytoskeleton

Answer 34

is a collection of filaments and cylinders that provide structural support, mobility and organisation.

Question 35

The cytoskeleton is divided into

Answer 35

Microfilaments (actin) - provide cell movement, muscle contraction, wound healing.
Intermediate filaments (such as keratin) - help give structural integrity to the cell and join with other cells to make 3D structures.
Microtubules (tubulin) - help transport things and are important during cell division.