Cellular Biology Flashcards
What are the 3 main parts to a cell?
1) the plasma membrane 2) the cytoplasm 3) the nucleus
What is the phospholipid bilayer?
Is permeable to water, gases, steroids and fat soluble vitamins
What do integral proteins do?
Assist small and medium sized water soluble substances across the membrane. They also act as a receptor for substances such as insulin
What are channel proteins?
Allow certain ions to move in and out of the cell
What are carrier proteins?
Change the shape as they move substances across the membrane
What are passive transport processes?
These do not consume energy (ATP) and move with the concentration gradient
What are examples of passive transport processes?
Diffusion and osmosis
What is simple diffusion?
Occurs when gases move across the phospholipid bilayer from a high concentration to a low concentration
What is facilitated diffusion?
Gases are assisted by channel and carrier proteins to move from high concentration to low concentration
What is osmosis?
Water moves across a selectively permeable membrane from an area of high water concentration to an area of low water concentration
What are active transport processes?
These use ATP and move against a concentration gradient
What are examples of active transport processes?
Active transport, Endocytosis and Exocytosis
What is active transport?
It requires ATP to push the gas into the cell. The most important active transport pump exchanges Na+ and K+ ions across the cell membrane to maintain homeostasis
What is endocytosis?
This involves phagocytosis (‘eating’ dead cells and bacteria) or pinocytosis (‘drinking’)
What is exocytosis?
Works in the opposite way to endocytosis and enables neurotransmitters, hormones, mucus and digestive enzymes
What is the cytoskeleton?
Helps to maintain the cells shape, holds organelles in place, enables cell contraction, cell division and enables the function of microvilli, cilia and flagella
What are the 6 main organelles?
1) Ribosomes 2) Endoplasmic Reticulum (ER) 3) Golgi body/ complex 4) Mitochondria 5) Lysosomes and 6) Nucleus
What are ribosomes?
They manufacture proteins in response to messages (mRNA) from the nucleus. Ribosomes attach to the ER and make proteins for export
What is the endoplasmic reticulum (ER)?
This is a network of folded membrane extends throughout the cytoplasm.
What does smooth ER do?
Makes lipids, steroidal hormones, detoxifies drugs and breaks down glycogen to glucose
What does rough ER do?
Makes proteins and phospholipids
What is the Golgi body?
Its main job is to concentrate, modify and package proteins and lipids for export or use in the cell membrane
What is the mitochondria?
These are complex organelles, with 2 layers of membrane that make ATP. They have their own DNA, RNA and ribosomes and are able to reproduce themselves
What are lysosomes?
These spherical membranous organelles are the cells demolition crew. They destroy bacteria, viruses, toxins and damaged organelles. They release calcium from the bones and glucose from glycogen. They break down unwanted tissue such as the uterine lining and webs between digits in the foetuses
What is the nucleus?
The control centre of the cell. Is round or oval and is usually the most prominent organelle. Most cells have a single nucleus often in the centre of the cell
What does the nucleus consist of?
1) The nuclear envelope 2) the nucleoli 3) nucleoplasm and 4) chromatin
What is the nuclear envelope?
This double membrane layer is similar to the mitochondria membrane. the outer layer is continuous with the rough ER and studded with ribosomes. It is punctured with nuclear pores
What is the nucleoli?
Typically there are 1 or 2 nucleoli per nucleus. Their job is to manufacture ribosomal subunits, these leave through the nuclear pores and combine to make ribosomes in the cytoplasm
What is nucleoplasm?
Is a jellylike fluid in which the other nuclear elements are suspended. It is similar to cytosol
What is chromatin?
The nucleus contains 46 chromosomes. In non dividing cells the chromosomes unwind to become chromatin. The total genetic information in cell is its genome
