chapter 2: cells :) Flashcards
what are the differences between a light microscope and an electron microscope?
- a light microscope can magnify objects only up to 1000x but an electron microscope magnifies up to 200,000x
- light micrographs: coloured image
electron micrographs: black and white image
what are cell membrane, nucleus and cytoplasm collectively known as?
protoplasm of a cell.
what are the organelles of an animal cell?
- cell surface membrane
- golgi apparatus
- ribosomes
- smooth endoplasmic reticulum
- rough endoplasmic reticulum
- nucleus: nucleolus & nuclear envelop
- cytoplasm
- mitchondrion
- small and numerous vacuole
what are the organelles of a plant cell?
- cell membrane
- golgi apparatus
- ribosomes
- smooth endoplasmic reticulum
- rough endoplasmic reticulum
- nucleus: nucleolus & nuclear envelop
- cytoplasm
- mitchondrion
- chloroplast
- vacuoles
- cellwall
what is the structure and function of the cell surface membrane?
structure: - made of lipids and proteins
- surrounds the cytoplasm
function: - partially permeable membrane that controls what enters and leaves the cell
what is the function of the cytoplasm?
- a jelly like substance and is where most of the cell activities occur
- contains organelles
what is the structure and function of the nucleus?
structure: - surrounded by the nuclear envelope
functions: - controls cell activities: cell growth and repair worn out parts
- essential for cell division
eg. cells such as red blood cells are unable to divide
what is the structure and function of the cell wall?
structure: -encloses the entire plant cell and is made of cellulose
- fully permeable
function: - it protects cell from injury and gives the plant cell a fixed shape
what are the functions of the nuclear envelope, nucleoplasm and nucleolus?
nuclear envelope: -separates the contents of nucleus from the rest of the cytoplasm
nucleoplasm: dense material within the nucleus
nucleolus: plays a part in making the protein the cell
what is the structure and function of chromatin?
structures: -long thread like structures
- made of proteins and compound called deoxyribonucleic acid or DNA
functions: -heredity stored in DNA & contains instructions that a cell needs to carry out activities
*when cells divide, it condense and become highly coiled, > chromosomes
what is the structure and function of the rough endoplasmic reticulum?
structure: - network of flattened spaces lined with a membrane
- ribosomes attach on its outer surface
- its connected to the nuclear envelope
function: - transports proteins made by the ribosomes to the golgi apparatus
what is the structure and function of ribosomes?
structure: - small round structures
- floating in the cytoplasm or attached to rough endoplasmic reticulum
functions:
- ribosomes attached to the RER usually make proteins that are usually transported out of the cell
- ribosomes lying freely makes protein that is used within the cytoplasm of the cell
what is the structure and function of smooth endoplasmic reticulum?
structure: does not have ribosomes attached to its membrane
- more tubular than RER
functions: -synthesises fats and steroids (hormones)
- converts harmful substances to harmless substances> detoxification
what is the function of a mitochondrion?
- small oval rod structure
- aerobic respiration occurs in the mitochondrion
- during this, food substances are oxidised to release energy
- energy can be used for cell activities, cell reproduction & cell growth
what are chloroplasts and whats the function of it?
- oval structures in the cell
- contains a green pigment called chlorophyll
> essential for photosynthesis which plants makes food
what are vacuoles and what are its functions in plant and animal cells?
- vacuoles are fluid-filled space enclosed by a membrane > it stores substances
in animals - many, small and temporary vacuoles
> stores water and food substances
in plants- large central vacuole and contains cell sap
- contains dissolved substances such as sugars, mineral salts and amino acids
- enclosed by a partially permeable membrane call tonoplast
what is the function of red blood cells and how has it adapted to its function?
function: transports oxygen from lungs to the rest of the body
- it has a circular, biconcave shape
> increase surface area to volume ratio so that oxygen can be taken in and released at a faster rate - it contains haemoglobin >binds to oxygen and transport it around the body
- it has no nucleus so that is is able to store more haemoglobin for transport of oxygen
how has xylem adapted for its function?
- long hollow tube> extending from roots to leaves
- has no cross-walls > to obstruct water flow through the lumen ( hollow space in the vessel)
-do not have protoplasm to offer resistance to the water flow
- the walls are thickened with lignin ( a woody substance) to prevent collapse of vessels
how has root hair cells adapted for its function?
- has a long and narrow protrusion/ extension (root hair)
> increases the surface area to volume ratio for faster rate of diffusion
what is a tissue?
- a group of cells with similar structures which work together to perform a specific function
what is a simple tissue and what is are some of the examples of it?
- cells of the same kind may group together to form a simple tissue
eg in humans: muscular tissue & epithelial tissue (skin tissue)
eg in plants: epidermis ( covers surface of leaves, stems and roots) & mesophyll tissue ( carry out photosynthesis)
what is a complex tissue and what are some examples of it?
- contains more than one type of cells
eg in human: blood (rbc,wbc, plasma, platelets)
eg in plants: - xylem consists mainly of vessels and dead cells - phloem tissue consists mainly of sieve tubes and companion cells
what is an organ?
- an organ contains more than one type of tissue, all working together for a specific function
what is an organ system and what are some examples?
- it consists of several organs working together for a common purpose
- digestive system, circulatory system, respiratory system and transport system
