Processes that sustain life: Cells and organelles Flashcards
Test review
What defines a prokaryotic cell
They are bacterial cells, have a simple structure and have no nucleus. DNA is concentrated in an area called a nucleoid that has no membrane around it. No membranes around any of its cell parts/organelles
What defines a eukaryotic cell
These are plant, animal, fungi and protist cells. Have a true nucleus in which DNA is enclosed by a membrane, as well as other more complex membrane bound organelles.
What is an organelle
A smaller component of a cell that has a specific function. All must work together to carry out the basic life processes of the cell.
What is a nucleus
Surrounded by a membrane called the nuclear membrane. The control center of the cell. Contains chromatin which is composed of smaller units called genes. Genes are made of DNA/deoxyribonucleic acid. Genes control the day by day activities of the cell by producing enzymes which control every chemical reaction in the cell. During cell reproduction the chromatin condenses to form chromosomes.
What is a nucleolus
A darker region within the nucleus that contains a very dense mat or ball of chromatin. Chromatin is long thin fibres of DNA and proteins that form chromosomes. The nucleolus produces ribosomes
What is cytoplasm
Made of the cytosol organelles, and all materials between the nuclear and the plasma membranes. The cytosol is the jelly-like fluid of a cell
What is ribosomes
Tiny organelles that make proteins from amino acids. Some flow free in the cytoplasm and produce proteins used by the cell itself. Other are found attached to the rough endoplasm reticulum (ER) and produce proteins which are usually used by other cells
What is an endoplasmic reticulum (ER)
A system of fluid filled canals which transport material around the cell. There is two types
What is the rough ER
Contains ribosomes and mainly transports proteins to the golgi body. Substances formed in the ER are transported to other parts of the cell by vesicles (small containers made of membrane used for storage and transport in/out of a cell)
What is the smooth ER
Has no ribosomes. As well as transporting materials it has detoxifying enzymes that break down various toxic chemicals. Liver cells have lots of smooth ER. Makes cholesterol which is an important part of cell membranes and forms many important hormones such as testosterone and more. Also releases calcium that is needed for muscle movement
What is the golgi body
Consists of stakes of flattened membranes. Main function is to transform newly made proteins into mature functional proteins and package them for transport outside the body. Proteins produced by ribosomes enter the rough ER. These proteins pinch off the ER into a tiny membrane bound sac called a vesicle, they then move to the golgi body and fuse with it. The protein passes through the layers and is changed chemically into a mature functional form, once again the protein will pinch off the golgi body in a vesicle that moves to the cell membrane and leaves the cell
What is the mitochondria
Generator of the cell, contains enzymes which release the energy stored in the food (CELL RESPIRATION). Consists of a double membrane, the outer separates it from the rest of the cell and the inner is extensively folded (cristae). Folding helps increase the surface area such that more enzymes can be produced to release more energy from food. Mitochondria contains their own DNA and ribosomes and grows and reproduces independently of the cell. All mitochondria in our bodies originated from our MOTHERS EGG CELLS. Cells that require extensive amounts of energy such as muscle cells, heart muscle, have 300-800x more mitochondria and they are generally more highly folded because these cells have high energy demands
What are lysosomes
Recycling centres of a cell, they contain enzymes which break apart and help digest large food molecules. These enzymes also recycle worn out, damaged/unwanted cells and cell parts.play a role in killing bacteria
What are vacuoles
The storage areas within a cell. They mostly contain water and are typically larger and more common in plant cells as they hold more water to keep the plant cell firm.
What are centrosomes
Contain a pair of centrioles, which are tiny organelles located near the nucleus that function in cell division (REPRODUCTION). Sometimes they appear star-shaped
What is the cytoskeleton
The internal support system of a cell. Is made up of microtubules and microfilaments. Microtubules are long hollow cylindrical structures and microfilaments are thin solid thread-like fibres. They can be assembled/disassembled in seconds. Microtubules are also responsible for the movement of chromosomes during cell division. if a cell has many short hair like structures composed of microtubules they are called cilia. If the microtubules form one or two long whip-like structures they are referred to as flagella
What defines cilia
Found in your lung cells, we have this to remove mucus as it traps dust and Bacteria. Found in the female reproductive tract to move the egg towards the uterus
Why do sperm cells have flagella
They have flagella for movement
What is the cell membrane
Forms a continuous boundary around the cell. is made up of a double layer of phospholipid, called a phospholipid bilayer. Heads of the phospholipids are water loving (hydrophilic) and the tails are water hating (hydrophobic). Embedded among the phospholipids bilayer are proteins which function in movement of certain materials in and out of the cell. Animal cells have also have cholesterol which allows them to function at a wide range of temperatures. Membranes are very fluid like in that the phospholipids flow from side to side. Because they have a variety of components and are very fluid like. Scientists refer to the cell membrane as the fluid mosaic model. They are also said to be selectively permeable in that they only allow certain materials to enter and leave the cell at certain times
What are some differences between plant and animal cells
-vacuoles are typically larger and more frequently found in plant cells
-plant cells have walls made of cellulose
-plant cells have chloroplast containing chlorophyll which is a green pigment. chlorophyll traps light energy from the sun and uses it to make food (carbs from carbon dioxide and water) PHOTOSYNTHESIS
-certain organelles such as lysosomes and centrioles are often absent from plant cells
What is chloroplast
Contains the green pigment chlorophyll which absorbs light energy from the sun and oxygen and uses it to make food (carbs/sugar) from carbon dioxide and water. this is PHOTOSYNTHESIS
What is a cell wall
A rigid structure which lies outside of the cell membrane. It is composed of cellulose and has three functions. supporting the cell, protecting the cell, and maintaining the cell shape
