The cell Flashcards
What is the plasma membrane and what is its function?
-forms a cell’s flexible outer surface, separating the cells internal and external environment
-it regulates the flow of materials into and out of a cell to maintain the appropriate environment for normal cellular activities
-also plays a key roll in communication among cells and between cells and the external environment
What is the structure of the plasma membrane?
-phospholipid bilayer made up of phospholipids, cholesterol and glycolipids
What is the function of integral and peripheral proteins within the plasma membrane?
-integral proteins extend through both layers and allow small water soluble materials to cross the membrane
-peripheral proteins are loosely attached to the surface of the membrane and have roles in cell signalling and communication
Describe the permeability of the plasma membrane
-selectively permeable
-allows some substances to move into and out of the cell but restricts the passage of others
What is the phospholipid bilayer permeable to? Give examples
-is permeable to water and non polar (lipid soluble) molecules e.g fatty acids, oxygen, carbon dioxide
What is the phospholipid bilayer non permeable to? Give examples
-isnt permeable to ions and large uncharged polar molecules e.g glucose and amino acids,
-proteins are able to be passed through using protein channels
What are the 8 types of body fluids?
-intracellular fluid- fluid in body cells
-extracellular fluid- fluid outside cells
-interstitial fluid- between cells in tissues
-blood plasma- in blood vessels
-lymph- in lymphatic vessels
-cerebrospinal fluid- surrounds brain and spinal cord
-solute- any material dissolved in a fluid
-solvent- fluid that dissolves materials
What is a passive process of transport?
-substance moves down its concentration gradient through the membrane, using only its own energy of motion
-includes simple diffusion and osmosis
What is an active process of transport?
-ATP is required to move the substance against its concentration gradient
-e.g active transport
Define the term diffusion
A passive process in which a substance moves due to its kinetic energy from an area of high concentration to an area of low concentration
What is the difference between simple diffusion and facilitated diffusion?
-simple diffusion substances diffuse through the bilayer on their own e.g fatty acids, steroids, oxygen, carbon dioxide
-facilitated diffusion uses an integral membrane protein to assist a specific substance moving through the membrane e.g a membrane channel or carrier
Define the term osmosis
A passive process in which there is a net movement of water through a selectively permeable membrane from an area of high water potential to low water potential
What is an isotonic solution?
When the concentrations of two solutes are the same so cells maintain their normal shape
What is a hypotonic solution?
a solution that has a lower concentration of solutes and a higher water potential
What is a hypertonic solution?
A solution that has a higher concentration of solutes and a lower water water potential
Define the term active transport
An active process in which cellular energy is used to transport substances across the membrane against its concentration gradient using energy from ATP
What is a vesicle and what is its function?
-A small round sac formed by budding off from an existing membrane
-they transport substances from one structure to another within cells, and carry out endocytosis (materials move into a cell) and exocytosis (materials move out of a cell)
What is a cell’s cytoplasm made up from?
-cytosol (the liquid portion of the cytoplasm)
-the cytoskeleton which provides a structural framework for the cell and generates movement. it is composed of microfilaments and microtubules
What is the organelle centrosome and what is its function?
-found in pairs at a 90 degree angle to one another, it organises and grows the mitotic spindle which plays a key role in cell division
What is the function of ribosomes?
The site of protein synthesis
What is the function of the endoplasmic reticulum and what is the difference between the rough and smooth ER in appearance and function
-a network of folded membranes of flattened tubules
-Rough ER extends from nuclear envelope and has ribosomes on its outer surface, synthesises proteins
-Smooth ER extends from rough ER and has no ribosomes, synthesises lipids
What is the function of the Golgi apparatus?
-to modify and package proteins
What are lysosomes?
-Membrane-enclosed vesicles that contain digestive enzymes
What are peroxisomes?
Contain several oxidases, which are enzymes that can oxidase various organic substances
What are proteasome?
Continuously destroy unneeded, damaged, or faulty proteins
What is the function and structure of the mitochondria?
-The site of respiration to produce ATP
-a series of inner folds called the cristae and a large central fluid-filled cavity
Describe the structures of the nucleus
-Nuclear envelope separates the nucleus and cytoplasm
-nuclear pores pierce the envelope and control the movement of substances between the nucleus and the cytoplasm
-nucleoli are clusters of protein, DNA, RNA and are the sites of assembly of ribosomes
-genes control cellular structure and direct cellular activities
-the genes are arranged along chemical chromosomes
Describe the process of protein synthesis
-DNA gene is transcribed to from RNA
-RNA attached to a ribosome where information in the RNA is translated into specific amino acids to from a new protein molecule
Describe the process of transcription
-genetic information in DNA base is copied into a complementary sequence of codons in a strand of RNA
-transcription is catalysed by the enzyme RNA polymerase
-mRNA, rRNA, and tRNA are made
Describe the process of translation
-when mRNA attaches to a ribosome and a protein is made by converting the sequence of nucleotides in mRNA into a specific sequence of amino acids
What is meiosis?
-reproductive cell division that produces gametes (sperm and oocytes)
What is mitosis?
-somatic cell division in which a body cell divides into 2 genetically identical daughter cells
What is the somatic cell cycle composed of and what happens in each stage of the cycle (including mitosis)
-in interphase the cell replicates its DNA
-in mitosis is where the nucleus and cytoplasm divides to form 2 identical cells through the stages of prophase, metaphase, anaphase, telophase
What is gerontology?
the scientific study of the process and problems associated with aging
