Ch. 2 - Cells Flashcards
What are cells?
Smallest units from which all organisms are made
What are microscopes used for?
To see cells clearly
What are the two types of microscopes?
- Light microscope
- Electron microscope
What are the pieces of a light microscope?
- Eyepiece
- Focussing knob
- Objective lenses
- Stage
- Mirror
How is the image of a light microscope called?
Photomicrograph
How is the image of an electron microscope called?
Electron micrograph
What does an electron microscope use?
Beam of electrons
What is a cell membrane?
Thin layer of protein and fat surrounding the cytoplasm
How is a cell membrane?
Partially permeable
What does partially permeable mean? What is a partially permeable thing?
Allows some molecules/ions to pass but not others
What’s the function of the cell membrane?
Controls what goes in and out
Can cell membrane be seen in plants?
Most likely no, as it is tightly pressed against the inside of cell wall
What is a cell wall?
A though layer usually made out of cellulose which surrounds cell membrane
In what is a cell wall found?
Plants, fungi, and bacteria
What is cellulose?
Something made out of polysaccharides
What does cellulose form?
Fibres which criss cross over one another
What is the function of the cell wall?
To prevent a cell from bursting when it absorbs too much water and swells
What is a characteristic of the cell wall?
It’s fully permeable
Why is the cell wall fully permeable?
Because it allows every molecule to pass through it thanks to the spaces between fibres
What is the cytoplasm?
A clear jelly which mainly contains water and can make up to 70% of some cells
What is contained inside the cytoplasm?
Substances, especially proteins
What takes place inside the cytoplasm?
Metabolic reactions
What are metabolic reactions?
Chemical reactions that take place in living organisms
What is a vacuole?
A fluid-filled space inside a cell surrounded by its own membrane
How are vacuoles in plant cells?
- Large and permanent vacuoles
- Solution of sugars called ‘‘cell sap’’
How does a vacuole work?
It presses outward on cell and keeps its shape
How are vacuoles in animal cells?
- Small
- Called ‘‘vesicle’’
What are vesicles?
Small vacuoles
What is a nucleus?
Part of the cell in which genetic information is stored
What are chromosomes?
Length of DNA contained in nucleus in which genetic information is stored
What is DNA?
A molecule that contains information and instructions to make proteins inside cells
What are the characteristics of chromosomes?
Thin and long
When chromosomes be seen? Why?
When the cell is dividing as they become shorter and thicker
Where are chloroplasts contained?
Into plant cells
What do chloroplasts contain?
Chlorophyll and starch grains
What are starch grains?
Tiny pieces of starch made by photosynthesis, never found in animal cells
What are mitochondria?
Part of the cell in which aerobic respiration takes place
What is aerobic respiration?
Chemical reactions which use oxygen to break down glucose and other nutrient molecules to release energy for the cell to use
Are mitochondria visible?
No, they’re invisible in a light microscope
What are ribosomes?
Tiny structures which are found in all animal and plant cells
What happens into ribosomes?
Information on DNA is used to make proteins out of long chain of amino in a particular sequence
What are the characteristics of bacterial cells?
- Cell wall which supports cell and stops it from bursting
- Partially permeable membrane
- Don’t have mitochondria and chloroplasts
- Prokaryotic cells
- Circle of DNA
- Plasmids
What are plasmids?
Small circles of DNA found in bacterial cells
What are specialised cells?
Cells which perform a particular activity
Ciliated cell, where and function?
Lining the trachea and bronchi of animals
Move mucus up
Neurone, where and function?
In the nervous system of animals
Conducting electrical impulses
Red blood cell, where and function?
In blood of mammals
Transporting oxygen
Sperm cell, where and function?
Testes of mammals
The male gamete in sexual reproduction
Egg cell, where and function?
Ovaries of mammals
The female gamete in sexual reproduction
Root hair cell, where and function?
Near the tips of the roots of flowering plants
Absorption of water and mineral ions
Mesophyll cell, where and function?
In the leaves of flowering plants
Photosynthesis
What is a tissue?
A group of similar cells which work together to perform a specific function
What are organs?
A group of tissues which work together to perform a particular function
What are organ systems?
A group of organs which work together to perform a particular function
