Organelles Flashcards
What are the two different types of cells? what is the difference? what organisms fit into these cell groups?
prokaryotic and eukaryotic.eukaryotuc cells contain membrane bound organelles. Bacteria and archaea are prokaryotes. Animals, plants, fungi and protists are eukaryotes.
what are the different classifications of organisms?
Bacteria, archaea, eukarya
What are the kingdoms in taxonomy? how are the organisms within them similar?
Animalia, plantae, fungi and protista. They all contain membrane bound organelles.
What is a prokaryotic cell?
relatively small and lack membrane bound organelles.
what are eukaryotic cells?
relatively complex and large cells. They have membrane bound organelles.
Do all organelles have membranes?
no
What different membranes do eukaryotic cells have?
they have a plasma membrane surrounding the cytoplasm but also internal membranes that form compartments (organelles)
What are enzymes?
proteins that act as catalysts and speed up reactions
what are the roles of organelle membranes? (2)
The membranes control the movement of substances between the organelle and the cells cytosol and it allows the organelle to have a different composition to the cytosol and other organelles.
What are the benefits of compartmentalisation? (3)
- allows enzymes and reactants for a particular reaction to be close together in high concentrations at the right conditions so that the organelles processes are efficient.
- allows processes that require different environments to occur at the same time, in the same cell
- makes the cell less vulnerable to changes in the environment, because changes will affect the cytosol more than the organelles.
What are cells?
the building blocks of life. They transport oxygen, nutrients and waste, synthesis proteins and produce new life.
How do different compartments communicate?
chemical messages (signals) help compartments communicate and ensure the cell is working well as a unit
What is the structure and function of the nucleus? Visibility?
-double membrane bound and it contains DNA. It contains hereditary information. light microscope
What is the structure and function of the rough endoplasmic reticulum? Visibility?
- It is membrane bound and is a system of cisternae. Ribosomes bind to its membrane.
- It processes and modifies proteins. electron microscope
what is the structure and function of the ribosomes? Visibility?
- They are made up of proteins and rRNA.
- they synthesis proteins by translating mRNA into it. the mRNA specifies the sequence of amino acids. electron
what are the structure and function of the Golgi Apparatus? Visibility?
- it is membrane bound and is made up of a stack of cisternae that are not connected to each other.
- It processes and packages proteins. electron
what is the structure and function of the lysosome? Visibility?
- it is a membrane bound vesicle that contains digestive enzymes
- digests cellular waste material and foreign matter
electron
what is the structure and function of the smooth endoplasmic reticulum? Visibility?
- it is membrane bound and a network of cisternae
- synthesises lipids
electron
what is the structure and function of the mitochondria? Visibility?
- It has a double membrane. the inner membrane is highly folded. It also contains DNA
- it obtains energy from organic compounds
electron
what is the structure and function of chloroplast? Visibility?
- a spherical or ellipsoidal with double membrane. It contains DNA and thylakoid sacs
- uses light energy, CO2 and eater to produce glucose.
light
what is the structure and function of a centriole? Visibility?
- small structure in the cytoplasm, consisting of microtubules
- involved in cell division and the formation of cell structures such as flagella and cilia
electron
what are the structures and functions of cilium and flagellum? Visibility?
- external structure consisting of microtubules
- involved in motility (the movement of substances across the surface of the cell
electron
what is the structure and function of the vacuole? Visibility?
- a membrane bound, fluid filled vesicle
- stores substances and is involved in cell structure in plant cells.
light
what is the structure and function of a plastid?
- small with a double membrane and contains DNA
- synthesises and storage of various organic molecules
What is the structure and function of a cell wall? Visibility?
- external structure surrounding the plasma membrane. Its composition depends on the type of cell.
- cell structure and protection. light
Do prokaryotic cells have any non-membrane-bound organelles?
yes but they are usually different in composition.
What organelles are not present in plants? (2)
lysosomes and sometimes centrioles.
what organelles are not present in animals? (2)
chloroplast and cell walls
Where is most of the DNA of a cell stored?
in the nucleus
How is the DNA in the nucleus organised? What is present in this DNA and what does this do?
in the form of linear chromosomes composed of DNA and protein. The information for synthesising proteins is present in the DNA and the genes in it are coped into messenger RNA which leaves and moves into the cytoplasm.
what is the most visible part of the nucleus? What is it made of? and what does it do? How can it be seen?
the nucleolus which is a non-dividing cell that is composed of proteins, DNA and RNA and it is where ribosomes are assembled.
How many ribosomes are there within cells and how big are they? How are they seen?
thousands and they are only 30nm in diameter so they can only be seen with an electron microscope.
What are ribosomes made up of?
two subunits that are joined together to form an 80S unit. One unit is 40S and the other is 60S
What places are ribosomes located? How does this change what they produce?
they are either free in the cytoplasm or bound to rough endoplasmic reticulum. Proteins produced by the free ribosomes function in the cytoplasm whilst proteins synthesised in the bound ribosomes are secreted out of the cell, packaged into organelles of inserted into the plasma membrane.
What is the ER and what are the differences between the two?
a network of intercellular membraneous sacs (cisternae) and tubles that link the plasma membrane with organelles. the Rough ER has ribosomes attached and the smooth ER does not.
What do the rough and smooth ERs do? where are they abundant?
RER- proteins from ribosomes pass through into its cavity and enzymes add sugar molecules to form glycoproteins. from there the proteins move to the Golgi body for export from the cell. abundant in cells that actively produce and export proteins eg. pancreatic cells that secrete digestive enzymes
SER- contains enzymes that produce molecules that aren’t proteins such as phospholipids and steroids. abundant in cells that secrete steroids like cells in ovaries.
How are vesicles formed and what do they do in the Golgi apparatus?
they form in the cisternae and transport proteins from one to the next, modifying them for use by the cell or for transport out of the cell. Vesicles budding out also carry membrane bound proteins to plasma membrane and digestive enzymes to lysosomes.
What are the two faces of the Golgi apparatus? How are they different?
The cis face and the trans face. The cis face of the cisternae is connected to the ER directly or indirectly (by small transport vesicles). The trans face is connected to the plasma membrane by large secretory vesicles. The membranes of the faces are like the ER and plasma membrane in composition.
What substances does the Golgi apparatus package but not export from the cell?
some like enzymes found in lysosomes are not released.
what sort of cells have the largest and most developed Golgi bodies?
secretory cells
How are lysosomes formed?
when a transporting vesicle containing enzymes is released from the golgi and fuses with another vesicle called called an endosome which contains molecules brought into the cell by endocytosis.
What do lysosomes do?
they fuse with vesicles containing containing waste (eg. damaged organelles) or foreign matter and enzymes in the lysosomes break it down. Small re usable molecules are diffused back into the cytoplasm but the rest is retained by the lysosome or released from the cell by exocytosis
what is exocytosis?
the fusion of a vesicle with the cell membrane, expelling its contents outside the cell.