Cell biology Flashcards
What is a cell
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.
What are the three main principles of cell theory
All living things are composed of one or more cells.
The cells is the basic unit of life.
New cells arise from existing cells.
What are the nine shapes of cells
Squamous Cuboidal Columnar Polygonal Stellate Spheroid Discoid Spindle-shaped Fibrous
What are the four main tissues found in the human body
Connective
Nervous
Muscle
Epithelial
Connective tissue
often forms joining structures in organ,
blood and bone are also considered connective tissue
Nervous tissue
It is electrically active and is part of the nervous system
Muscle tissue
Is further divided into skeletal, smooth and cardiac muscle
Epithelial tissue
Forms linings on our organs
How are cells studied
Through
microscopy - Structural information
Biochemical analysis - functional information
Types of Microscopy
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)
Biochemical Analysis
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.
What are the cell domains
Prokaryota ( Bacteria and Archaea)
Eukaryota
What are the common features to all cells
Plasmar membrane
Semi-fluid substance - cytosol
Chromosomes - carry genetic information
Ribosomes - make proteins
Characteristics of Prokaryotic cells
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
Characteristics of Prokaryotic cells
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
Characteristics of Eukaryotic cells
Have membrane-bound organelles
DNA is packed with in the nucleus and organised in chromosomes
Their size ranges between 10 to 100 muM
organelles
Plasma membrane Nucleous Endoplasmatic reticulum Golgi apparatus mitochondria lysosomes ribosomes (Cytoskeleton)
Plasma membrane
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.
Nucleous
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
What is a Nucleolus
It is a specialised region fo the nucleous where ribosomes are produced.
What is DNA built up from
Nucleotides,
Each include a nitrogenous base ( purines - 2 rings or pyrimidine, 1 ring);
A pentose sugar (Desoxyribose)
and a phosphate group
What is the structure of DNA like
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).
Adenine pares with
Thymine
Guanine pares with
Cytosine
Uracil substitutes … in RNA
Thymine
Endoplasmatic Reticulum
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.
Sooth ER
Produces molecules like steroids, other lipids and glucose. in muscle cells it specializes in CA+2 storage, in liver cells it specializes in detoxification
Rough ER
Has ribosomes which are responsible for protein production
Golgi Apparatus
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.
How are proteins synthesised
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.
Mitochondria
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.
Sugar into ATP
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.
Lysosomes
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.
The cytoskeleton
is a collection of filaments and cylinders that provide structural support, mobility and organisation.
The cytoskeleton is divided into
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.
