Chapter Two: Membranes And Cell Organelles Flashcards
Identify and describe the 2 main pathways of apoptosis.
Mitochondrial pathway:
If serious damage occurs INSIDE the cell (e.g. DNA damage) proteins on the surface of mitochondria are activated & mitochondrial membrane breaks. Cells may also initiate death of infected by a virus.
Death receptor pathway:
OUTSIDE CELL
Receive messages to self destruct because it may not be fully developed, more than you need, outlived your usefulness. Cell membranes have death receptors to receive these.
What happens if there is too much or not enough apoptosis?
Too much= can lead to neurodegenerative diseases such as Alzheimer’s and Huntington’s disease.
Too little= can lead to the production of cancers and autoimmune diseases.
What does diffusion mean? What does channel and carrier mediated diffusion refer to?
Diffusion: net movement of substance-that doesn’t require energy-from HIGH concentration to LOW concentration.
Channel mediated: unable to carry out simple diffusion so gain free passage with the assistance of protein channels.
Carrier mediated: carrier molecule is required to move molecules through the channels.
What is osmosis?
Net movement of water molecules by diffusion across a cell membrane.
HYPOtonic to HYPERtonic.
What is active transport?
Net movement of dissolved substances into/out of a cell, against concentration gradient.
Requires energy and involves a carrier protein for each substance that’s actively transported.
Enables cells to maintain homeostasis in spite of external surrounding variation. LOW to HIGH
What is phagocytosis and pinocytosis?
Phago: bulk material taken into a cell as a solid.
Pino: bulk material taken into a cell as a fluid.
What is endocytosis and exocytosis?
Endo: the process of bulk transport of material into a cell.
Exo: the process of bulk transport of material out of a cell.
What is a nucleus?
The control centre of the cell. Enclosed within a double membrane (nuclear envelope). Cells with a membrane-noun nucleus are eukaryotic. DNA is usually dispersed within nucleus.
What is a mitochondrion?
ATP produced during cellular respiration occurs in mitochondria. Form part of the cytoplasm. Has an outer membrane and a highly folded inner membrane. ATP is produced by reactions that occur on the inner folded membrane.
What are ribosomes?
Protein production, part of the cytoplasm, not enclosed by a membrane. Composed of proteins and RNA.
What is apoptosis?
Programmed cell death. Self destruction by cells for the good of the whole organism.
What does the endoplasmic reticulum do?
Transport of substances within the cell.
What is the Golgi complex (apparatus)?
Consists of several layers of membrane. Packages protein Ito vesicles for transport out of cell.
What are lysosomes?
Sac-like structures surrounded. Y a membrane and filled with a fluid containing dissolved digestive enzymes. Part of the cytoplasm. Use their enzymes to destroy unwanted parts of a cell or damaged molecules within or outside the cell.
What is the cell skeleton?
Supporting structure of an internal framework of protein micro tubules, microfilaments and intermediate filaments.
MICROTUBULES are hollow and are made of sub units of the protein tubulin. Important in movement of chromosomes and reproduction of cells.
MICROFILAMENTS are solid, thinner and more flexible and are made of actin.
INTERMEDIATE FILAMENTS are made of a variety of proteins (depending on the particular cell) and are very tough. They often tie into the cytoskeleton of other cells.
