Life at the Cellular Level Flashcards
What is the cell?
The functional unit of all living things
Why are cells so small?
So there is an increased surface area for essential cellular processes such as diffusion
What is the main difference between a prokaryote and eukaryote?
Eukaryote has a nucleus
Prokaryote does not have a nucleus
Describe a prokaryotic cell
Lack nuclear membrane
No mitochondria
Have no membrane bound structures
Have DNA but it is not bound in a membrane
Describe a eukaryotic cell
Have a nucleus with a nucleus membrane
Have membrane bound structures
What is a stem cell?
Unspecialised cell that differentiates to become a specialised cell
What is a totipotent stem cell?
Has total potential
Can give rise also to both embryonic and placenta cells
What is a pluripotent stem cell?
Can develop into all cell types in the body but not placenta or embryonic
Multipotent
cells such as those from bone marrow which can differentiate into specific groups of cells
Multipotent do not have total potential
Describe differentiation
Different genes are expressed meaning that different proteins are made - its the proteins in a cell that determine that cells function
How do cancerous cells divide?
without any control or co-ordination
Normally what will happen to a damaged cell?
It will undergo apoptosis
What is apoptosis?
Programmed cell death
Apoptosis is intimately coupled with what other process?
Cell proliferation
What are the 4 different types of tissues in the body ?
Epithelial
Connective
Nerve
Muscle
What is the order from cells to organisms?
Cell, tissue, organ, system , organism
What component makes up the cell membrane?
Lipids
What is the function of the plasma membrane?
To act as as elective barrier for the cell
Membrane lipids are amphipathic what does this mean?
Means they have a hydrophilic head and a hydrophobic tail
Some proteins in the membrane span the entire cell membrane what are these called?
Integral proteins
Other proteins only make contact with the cell membrane what are these known as?
Peripheral proteins
Does passive diffusion require energy?
No
Does active transport require energy?
Yes
Explain active transport
Process that requires energy to move against a concentration gradient, usually in the form of ATP
Explain passive diffusion
No energy is required as it moves down a concentration gradient
What is endocytosis?
When something is engulfed into the cell - the membrane is invaginated and is stored in a vesicle
What is exocytosis?
When something is released from the cell, for example a neurotransmitter being released in a vesicle
What are gap junctions in cell adhesion?
small passages that allow the movement of small water soluble molecules from cell to cell
Where are endocrine signals carried?
In the blood
What is the RER studded with?
Ribosomes
Which cells do not contain mitochondria?
RBC
What do mitochondria have their own of?
DNA
Why do mitochondria have their own DNA?
Because they synthesis most of their own proteins
Why is the double membrane in mitochondria so important?
Because it allows for the H+ gradient to be formed at the ETC
Where is most of the energy from respiration generated?
In the mitochondria
What does the nucleus contain?
DNA, nucleoprotein and some RNA
What are heterochromatin?
Denser areas where DNA is still coiled - not expressing
What it euchromatin?
Lighter areas where DNA is unwrapped and active- is expressing
What does the golgi apparatus do?
Takes in proteins from the ER to be modified in some way
What do lysosomes separate?
Enzymes from the rest of the cell
Why are lysosomes so important?
Because they store digestive enzymes in vesicles so they don’t harm the rest of the cell
What are cilia and flagella made of?
Microtubules
Which is longer cilia or flagella?
Flagella
Give an example of where cilia are found
Lining the respiratory tract
What bond are amino acids linked by?
Peptide bonds
Is rNA single or double stranded?
Single stranded
What base replaces thymine in rNA?
Uracil
What can free energy be used to define?
The spontaneity of a reaction
A spontaneous reaction must decrease what and increase what?
Decrease enthalpy
Increase Entropy
What is the problem with G=0?
It is incompatible with life
What does free energy flow between?
Catabolic and anabolic processes
What is each step in a metabolic pathway catalysed by?
An enzyme
