1-Cells and Molecules Flashcards
Life at the cellular level.
Structures and features present in prokaryotic cells.
Cell membrane, cell wall, ribosomes, plasmids, cytoplasm, nucleoid, pili, flagella.
Lacks nuclear membrane, no membrane bound organelles.
Structures and features present in eukaryotic cells.
Cell membrane, ribosomes, cytoplasm, rough and smooth endoplasmic reticulum, Golgi apparatus, lysosomes, mitochondria = lots of membrane bound organelles.
Define the roles of the nucleus
The nucleus controls all cell activity, and is essentially the brain of the cell, storing genetic information - DNA.
Nucleoids are sites of ribosomal RNA synthesis and ribosome assembly.
The nucleus is contained within the nuclear membrane/envelope, that is, like all other biological membranes a phospholipid bilayer. This is closely associated with the Endoplasmic Reticulum.
Define the roles of the Endoplasmic Reticulum.
The endoplasmic reticulum is a membrane bound organelle.
It comes in two forms - the RER and the SER.
The RER has ribosomes on its cytosolic face, ribosomes synthesise proteins and the RER modifies them.
The SER lacks ribosomes and is associated with lipid and steroid hormone productions and metabolism of toxins.
Define the roles of the Golgi apparatus.
The Golgi apparatus is arranged in a series of flattened membrane discs, (easy to identify on microscope?).
The Golgi apparatus packages proteins and prepares them for transport out of the cell.
Define the roles of a lysosome.
Lysosomes are membrane bound organelles that contain a variety of enzymes.
These enzymes are an example of a protein that has been packaged into a vesicle by the Golgi, in order to keep them separate from the rest of the cell.
These enzymes are referred to as digestive or degradative and they are responsible for the digestion of biological materials (eg. cells own materials; autophagy) and digestion of engulfed particles (eg. bacteria)
Define roles of a peroxisome.
Peroxisomes are membrane bound organelles containing enzymes, they keep the enzymes separated from the rest of the cell.
Peroxisomal enzymes degrade long-chain fatty acids and other foreign toxic chemicals. These reactions generate hydrogen peroxide, which is toxic. Peroxisomes break down hydrogen peroxide (catalase enzymes) protecting the cell.
Define the roles of the mitochondria.
The mitochondria is the site of aerobic respiration.
They are organelles bound by a phospholipid bilayer.
Outer membrane has pores.
Inner membrane has folds (cristae), which gives the mitochondria more surface area.
The matrix contains many of the enzymes required for metabolising food molecules.
Define the roles of flagellum and cilium.
Flagella and cilia are surface projections supported by the cytoskeleton.
Flagella and cilia have 9 pairs of microtubules surrounding a central pair.
Flagella are the longer of the two, usually one or two present, movement is snakelike.
Cilia are short, usually many present, move with stiff power stroke and smooth recovery stroke.
Describe the structure and function of the eukaryotic plasma membrane.
The cell membrane, also referred to as the plasma membrane is composed of a double layer formed by phosphate proteins and lipids = phospholipids. This forms a selective barrier only letting certain molecules into the cell.
Embedded in the bilayer are proteins that act as receptors, detecting chemical messengers and signalling molecules, allowing signals from the extracellular fluid to be transduced or transported into the cell.
Define the role of the cytoskeleton.
The cytoskeleton supports and maintains cell structure.
Holds organelles in place - 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 and describe cell differentiation.
Stem cells can be multi or pluripotent.
Undifferentiated stem cells divide and give rise to daughter cells, which are genetically identical.
Differences in gene expression and different local environments causes daughter cells to develop into different cell types.
Outline the difference between apoptosis and necrosis.
Apoptosis is programmed and controlled cell death, it is vital for normal function.
Necrosis is not controlled and is in short, death, as a response to infection or injury.
Define the major elements used to construct human biomolecules.
Most cells are composed primarily of:
Hydrogen, Oxygen, Nitrogen and Carbon;
Which are the lightest atoms able to make 1,2,3 and 4 bonds respectively.
State the importance of chemical functional groups, molecular configuration and conformation in determining biomolecular function.
Biomolecular molecules can have more than one functional group present in its conformation.
They can also have C=C double bonds and this restricts rotation of bonds, meaning to rearrange the placement of functional groups there is a great deal of energy required.
