3.1 - 3.4 : Prokaryotic and Eukaryotic Cells Flashcards
What are all living organisms are made up of ?
all living organisms are made of one or more cells
Name the 3 points of the cell theory
- All living organisms are made of cells.
- The cell is the building block of life in all living things.
- All cells are produced by the division of pre-existing cells.
There are two fundamentally different types of cell:
Prokaryotic and Eukaryotic
Example of Prokaryotic cells (Prokaryotes)
Bacteria and Archaea - They are unicellular meaning they are single-celled organisms.
Examples of Eukaryotic cells (Eukarya)
Protist, Plant, Animal, Fungi - They can be Unicellular or Multicellular
- Eukaryotic means ‘true nucleus’
Prokaryotic cell features
- No nucleus or chromosomes
- DNA is not associated with any histone proteins and lies free in the cytoplasm
- Peptidoglycan cell wall always present
- No membrane bound organelles e.g. mitochondria
- Vast in number
- Extremely small (0.5-5µm) - much smaller than eukaryotic cells
- Cytoplasm
- Mesosme
- Cell wall
- Small ribosmoes
Similarites of Prokaryotic cells and Eukaryotic cells
- Both have DNA (genetic material)
- Both have ribosomes (small organelles that make protien)
- Both have cytoplasm (jelly fluid within cells)
- Both have a cell membrane (aka plasma membrane which controls what goes in and out of the cell, maintaining homeostasis)
Name all the parts of the ultra structure of eukaryotic cells.
nucleus, nucleolus,
ribosomes, rough and smooth endoplasmic reticulum (RER and SER) , mitochondria, centrioles,
lysosomes, and Golgi apparatus
Name all the parts of the ultra structure of prokaryotic cells.
cell wall, capsule,
plasmid, flagellum, pili, ribosomes, mesosomes and circular DNA.
The nucleus functions.
- Only eukaryotic cells have a nucleus.
-
Functions :
- Production of mRNA for protein synthesis
- Retain the genetic material of the cell in the form of
DNA - Manufacture ribosomes
- To start the process of cell division.
Name all the parts in the nucleus
-
Endoplasmic reticulum :
- rough and smooth - Nucleolus
- Chromatin
- Nucleoplasm
- Nuclear pore
- Nuclear envelope
- Ribosome
RER
Rough Endoplasmic Reticulum (RER)
RER is formed from folds of membrane continuous with the nuclear envelope (it’s an extenstion of the nuclear envelope)
The surface of RER is covered in ribosomes
It facilitates protein synthesis by providing a large surface area for ribosomes. It then transports the newly synthesised proteins to the Golgi apparatus for modification.
Smooth endoplasmic reticulum (SER)
- SER is also formed from folds of membrane but its function is distinct from the RER, it synthesises lipids including cholesterol and steroid hormones (such as oestrogen).
- SER does not have ribosomes on its surface
Nucleolus
- The nucleolus is the largest nuclear organelle.
- The function is to produce and assemble the cell’s ribosomes. The nucleolus is also where ribosomal RNA genes are transcribed.
Chromatin
- Chromatin is composed of nucleosomes, which are a complex of DNA and proteins.
- Chromatin is a thin and long fibre
- Found throughout the cell cycle.
- The main function of chromatin is to package DNA into a unit capable of fitting within the tight space of a nucleus.
Nucleoplasm
- The fluidlike substance in the nucleus of a cell in which the nucleolus and chromatin are suspended.
- The principal function of the nucleoplasm is to program as a suspension substance for the organelles inside the nucleus.
Nuclear pore
- Nuclear pores are tiny openings present in the nuclear membrane of the nucleus. They are formed by the fusion of two nuclear membranes.
- Function : allows small molecules and ions to freely pass, or diffuse, into or out of the nucleus.
The nuclear envelop
The nuclear envelope (NE) is a highly regulated membrane barrier that separates the nucleus from the cytoplasm in eukaryotic cells, and provides the structural framework of the nucleus.
Ribosome
A ribosome is an intercellular structure made of both RNA and protein, and it is the site of protein synthesis in the cell. The ribosome reads the messenger RNA (mRNA) sequence and translates that genetic code into a specified string of amino acids, which grow into long chains that fold to form proteins.
Prokaryotic vs Eukaryotic
Eukaryotic organisms have membrane bound organelles
- Eukaryotic organisms contain a named-bound organelle
- Size of ribosmomes are lrg
The Golgi apparatus
- A group of fluid filled membrane-bound flattened sacs surrounded by vesicles.
- Modify + package proteins and lipids
- Package them into secretory vesicles for transport
- They also make lysosomes ( a special type of Golgi vesicles) the site of lysosome synthesis.
Mitochondria
- Site of ATP production during aerobic respiration.
- It is self-replicating so can become numerous in cells with high energy requirements.
- It contains a double membrane with folds called cristae, which provides a large surface area for respiration.
Chloroplasts
-the site of photosynthesis.
- It is enclosed by a double membrane and has internal thylakoid membranes arranged in stacks to form grana linked by lamellae.
- These structures are found only in plants and certain types of photosynthesising bacteria or protoctists.
Cell wall
a rigid structure made of cellulose (in plants),chitin (in fungi) and murein (in prokaryotes) which provide support to the cell.
Vacuole
the vacuole is an organelle which stores cell sap and may also store nutrients and proteins. It helps to keep plant cells turgid. Some vacuoles can perform a similar function to lysosomes and digest large molecules.
Centrioles
- these are bundles of microtubules which form spindle fibres during mitosis in order to pull sister chromatids apart.
- They are also important for the formation of cilia and flagella. They are not found in plant and *bacterial cells.
- Provide structural support (cytoskeleton)
- Guide and direct movement of cell organelles.
Protein production steps and stages
- Nucleus contains the gene for the protein which is the site of transcription (DNA to mRNA)
- Translation of mRNA into a polypeptide chain takes place on chromosomes which are either floating alone in the cytoplasm or attached to the rough ER.
The long polypeptide chain is folded at the rough ER and transported to the Golgi apparatus inside vesicles.
Golgi body modifies the protein
e.g adds a carbohydrate group so it becomes a glycoprotein
Protein is package into Golgi vesicles
vesicle is transported into the cell surface membrane
exocytosis - vesicle fuses with the membrane
e.g extracellular enzyme
Pro vs Euk
- Eukaryotic organisms have membrane-bound organelles
- The DNA in eukaryotic organisms are asscoiated with histone protiens.
- 70s ribosomes = Pro
- 80s ribosomes = Euk
- Eukaryotic organisms do not contain plasmids.
Describe what happens to lysosomes once their contents have been digested.
DNA synthesis in bacterial cell cultures has been investigated.
Describe how DNA is organised in a bacterial cell.
(3)
Describe what happens to lysosomes once their contents have been digested.
(2)
Scientists took blood samples from infected red squirrels and analysed them using an
electron microscope.
Describe the features that could be used to identify the prokaryotic cells in the blood
sample.
(4)
Explain why the nucleus cannot be observed at the end of prophase in a eukaryotic cell.
(2)
Give two functions of the Golgi apparatus.
(2)
A three-phase protocol will be used when developing the phospholipase inhibitor as a
new drug.
Explain the purpose of each phase of this protocol for a phospholipase inhibitor.
(3)
Many of the proteins synthesised become extracellular enzymes.
Describe what happens to these proteins following the process of translation until they
are released from the cell.
(3)
