Life at the Cellular level 1- the cell Flashcards
What are the differences between eukaryotic and prokaryotic cell types?
Prokaryotic cells such as Bacteria and archaea lack a nuclear membrane and have no membrane bound organelles. Eukaryotic cells such as Animals, plants, fungi, algae and protozoa have a nucleus with membrane and have membrane bound organelles.
What is the role of the nucleus?
Contains DNA - the brain of the cell.
Nucleoli are sites of ribosomal RNA synthesis and ribosomal assembly.
The nucleus is enclosed in the nuclear membrane/envelope which, like all biological membranes, is a phospholipid bilayer.
It is closely associated with the Rough Endoplasmic Reticulum.
What is the role of endoplasmic reticulum?
Endoplasmic reticulum comes in rough (RER) and smooth (SER) varieties.
RER has ribosomes attached giving it the “rough” appearance
RER modifies proteins.
SER has no ribosomes attached and is mainly associated with lipid and steroid hormone production and metabolism of toxins.
What is the role of ribosome?
Ribosomes synthesise proteins
What is role of golgi apparatus?
Golgi Apparatus packages up protein in preparation for transport out of the cell.
What are roles of lysosomes?
Lysosomal enzymes are degradative and they are responsible for the digestion of biological materials (cells own materials; autophagy) or digestion of engulfed particles (e.g. bacteria).
What are roles of peroxisomes?
Peroxisomal enzymes degrade long-chain fatty acids and other foreign toxic molecules. These reactions generate hydrogen peroxide, which is toxic. Peroxisomes break the hydrogen peroxide (catalase enzyme) protecting the cell.
What are peroxisomes and lysosomes?
Lysosomes and peroxisomes are membrane bound vesicles containing enzymes – they separate enzymes from the rest of the cell.
What is role of mitochondria?
Mitochondria are also organelles bound by a phospholipid bilayer.
Outer membrane contains pores.
Inner membrane has cristae (folds).
Matrix contains most of the enzymes required for metabolising food molecules (e.g. Krebs cycle).
They have their own circular DNA.
They have their own ribosomes – similar to bacterial ribosomes.
They synthesise most of their own proteins.
They can self-replicate.
What is role of flagellum?
Organelle used by cell for movement , longer, usually one or two present, movement is snakelike. Example sperm cell
What is role of cilia?
Organelle used by cell for movement. Short, usually many present, move with stiff power stroke and flexible recovery stroke.
Describe structure and function of plasma membrane/ plasmalemma?
Comprises a double layer of lipid with attached phosphate groups = phospholipid bilayer.
Forms a selective barrier, being choosy about what it allows to cross in or out of the cell.
Embedded in the membrane are proteins which act as receptors to detect chemical messengers and signalling molecules in the fluid surrounding cells (extracellular fluid).
Describe role of cytoskeleton?
Supports and maintains cell shape.
Holds organelles in position – internal cell order.
Helps move organelles around the cell – intracellular transport.
Drives and guides cellular migration – movement.
Protein fibres of the cytoskeleton connect with protein fibres in the extracellular space – Assembly of cells into tissues.
Define stem cells ?
Stem cells are cells that can differentiate into many (multipotent) or any (pluripotent) cell types of the body.
