Organization of the organism Flashcards
What are the main features of animal cells?
- Animal cells often have an irregular shape
- They have the following features: cell membrane, cytoplasm, nucleus, mitochondria, ribosomes
- They feed on organic substances made by other living things
- They often store carbohydrates as glycogen
- They usually have nervous coordination
- They are able to move from place to place
What are the main features of plant cells?
- They have a regular shape (because of cell wall)
- They have the following features: nucleus, cytoplasm, cell membrane, mitochondria. ribosomes, cell wall, chloroplasts, permanent vacuole
- They store carbohydrates as starch or sucrose
- They do not have nervous coordination
What is the function of the nucleus?
Contains the genetic material (DNA) which controls the activities of the cell
What is the function of the cytoplasm?
- A gel like substance composed of water and dissolved solutes
- Made of two parts: organelles and cytosol (fluid that gives cell shape)
- Site of many chemical reactions including anaerobic respiration
What is the function of the cell membrane?
- Holds the cell together, separating the inside from the outside
- Controls which substances can enter and leave the cell
- Semi permeable and thin
What is the function of ribosomes?
- Can be free floating in the cytoplasm or associated with the ER
- Site of protein synthesis (makes proteins)
What is the function of the mitochondria?
- Double membrane
- Site of cellular respiration
- Converts glucose into ATP that our cells can use
What is the function of the cell wall?
- Made of cellulose (a polymer of glucose)
- Gives the cell extra support, defining the shape
What is the function of chloroplasts?
- Contains green chlorophyll pigment (to absorb light energy) and the enzymes needed for photosynthesis
- Uses light energy to produce glucose as a food source
What is the function of a vacuole?
- Plant cells have a large central vacuole
- Animal cells have several small vacuoles or absent
- Important for storage of compounds, water and nutrients
- Maintains turgidity
What are the features of bacteria?
Cell membrane, cytoplasm, ribosomes, cell wall (made of peptidoglycan), circular loop of DNA
Some may also have plasmids (small loops of DNA) and flagella (thread like structures that allow them to move in liquids)
What do bacteria cells not have?
Internal membranes
Compare and contrast the structure of bacterial cells and plant cells (3)
- Both have cell membranes (1)
- Both have ribosomes (1)
- Bacterial cell walls are made from peptidoglycan while plant cell walls are made of cellulose (1)
- Bacteria have no internal membranes while plant cells have a nucleus/chloroplast/mitochondria (1)
What are specialised cells?
Specialised cells are those which have developed certain characteristics in order to perform particular functions. These differences are controlled by genes in the nucleus
How do cells specialise?
By undergoing the process of differentiation: A process where cells develop the structure and characteristics needed to be able to carry out their functions
Why do cells need to divide?
to help your body grow and repair itself
How are new cells produced?
The division of existing cells
What’s the function of a ciliated cell?
Movement of mucus in the trachea and bronchi
What’s the function of a neuron?
Sending and recieving neurotransmitters
What’s the function of an egg cell (ovum)?
Reproduction
What’s the function of a sperm cell?
Reproduction
What’s the function of a red blood cell?
Transport of oxygen
What are the adaptations of a ciliated cell?
- Extensions of the cytoplasm at the surface of the cell form hair-like structures called cilia which beat to move mucus and trapped particles up the throat
What are the adaptations of nerve cells?
- Long so nerves can run to and from different parts of the body to central nervous systems
- The cell has extensions and branches, so that it can communicate with other nerve cells, muscles and glands
- The axon (extension of cytoplasm away from the cell body) is covered with a fatty sheath, which insulates the nerve cell and speeds up the nerve impulse
What are the adaptations of red blood cells?
- Biconcave disc shape increases surface area for more efficient diffusion of oxygen
- Contains haemoglobin which joins with oxygen to transport it
- Contains no nucleus to increase amount of space available for haemoglobin inside cell
What are the adaptations of a sperm cell?
- The head contains the genetic material for reproduction in a haploid nucleus (nucleus with half the normal number of chromosomes)
- The acrosome in the head contains digestive enzymes so that a sperm can penetrate an egg
- The mid-piece is packed with mitochondria to release energy needed to swim and fertilise the egg
- The tail enables the sperm to swim
What are the adaptations of an ovum?
- Contains a lot of cytoplasm which has nutrients for the growth of the early embryo
- Haploid nucleus contains the genetic material for fertilisation
- Cell membrane changes after fertilisation by a single sperm so no more sperm can enter
What is the function of root hair cells?
Absorbtion of water and mineral ions from water
What is the function of the xylem vessel?
Conduction of water through the plant; support of the plant
What is the function of a palisade mesophyll cell?
Photosynthesis
What are the adaptations of a root hair cell?
- Root hair increases surface area of cell to ensure maximum absorption of water and mineral ions
- Walls are thin enough to ensure that water moves through quickly
- No chloroplasts present
What are the adaptations of the xylem vessel?
- No top and bottom walls between xylem vessels so there is a continuous column of water running through them
- Cells are dead without organelles or cytoplasm to allow free passage of water
- Their walls become thickened with a substance called lignin which means they are able to help support the plant
What are the adaptations of the palisade mesophyll cell?
- Column shaped to maximize absorption of sunlight and fit as many in a layer under the epidermis of the leaf as possible
- Contains many chloroplasts for maximum photosynthesis
What’s the first level of organisation in an organism? describe it.
Cell. Basic functional and structural units in a living organism
What’s the second level of organisation in an organism? describe it.
Tissue. Groups of similar cells working together to carry out a specific function
What’s the third level of organisation in an organism? describe it.
Organs. Groups of tissue working together to carry out a specific function.
What’s the fourth level of organisation in an organism? describe it.
Organ system. Groups of organs working together to carry out a specific function.
What’s the magnification equation?
M=Image size/actual size
How many micrometers is a millimeter?
1000μm
