Cells Flashcards
Active transport
movement of particles against a concentration gradient, requires energy
Bacterium
single celled microorganism
Binary fission
simple cell division in prokaryotic cells
Cell cycle
growth and division stages of cells
Cell elongation
the enlargement of a cell, plant cells grow by cell elongation
Cell membrane
thin surface which surrounds a cell
Cell wall
structure around some plant cells that provides support
Cellulose
plant molecule that strengthens cell walls, also algae
Chlorophyll
green substance in chloroplasts, absorbs light for photosynthesis
Chloroplast
structure in plant and algae cells for photosynthesis, contains chlorophyll
Chromosome
a long length of coiled up DNA, which carries genes
Culture
population of one type of microorganism, grown under controlled conditions
Cytoplasm
gel-like substance in cell where most chemical reactions take place
Differentiation
specialisation process in cells
Diffusion
moving out of particles from area of high concentration to one of low
Electron microscope
device to create images of small things by use of electron particles, not light
Eukaryotic cell
complex cell, such as plant or animal
Exchange surface
thin surface with holes, allows smaller particles to pass through
Fungus
unicellular microorganism such as fungus, yeast and moulds, useful decomposers, can cause harm to other organisms
Gamete
sex cell, e.g. an egg cell or a sperm cell in animals
Gene
short section of DNA, found on a chromosome, controls the development of a characteristic
Guard cell
cell in pairs that open and close stoma (hole) in plant leaves
Mitochondria
structure in cells, site of aerobic respiration
Multicellular organism
made of more than one cell
Nucleus (of a cell)
structure in a body cell, contains genetic material information in form of chromosomes
Osmosis
diffusion of water molecules across a partially permeable membrane
Partially permeable membrane
thin surface with holes, allows smaller particles to pass through
Permanent vacuole
structure in plant cells, contains nutrients and wastes in water solution
Phloem
plant tissue ‘tubes’, transport dissolved sugars
Prokaryotic cell
small, simple cell such as bacterium
Resolution
ability of microscope to distinguish two objects
Ribosome
structure where proteins are made
Root hair cell
long narrow cell on end of plant roots, absorbs water and minerals
Specialised cell
performs one job
Stem cell
undifferentiated cell, unspecialised, able to change and specialise
White blood cell
part of the immune system, helps defend the body against infection, many sub-types
Xylem
plant tissue ‘tubes’, transporting water and minerals upwards
What is a defining feature of eukaryotic cells?
Their genetic material (DNA) is enclosed within a nucleus
This distinguishes eukaryotic cells from prokaryotic cells, where DNA is not enclosed in a nucleus.
What is the typical size range of eukaryotic cells?
Usually between 10 and 100 µm
This size range can vary based on the type of eukaryotic organism.
What is a defining feature of prokaryotic cells?
Their genetic material is not enclosed within a nucleus
What shape is the genetic material found in prokaryotic cells?
A single loop of DNA
Where is the genetic material located in prokaryotic cells?
Within the cytoplasm
What are additional smaller circular pieces of DNA found in prokaryotic cells called?
Plasmids
What surrounds the cell membranes of all prokaryotic cells?
A cell wall
What is the substance usually used to make the cell wall of prokaryotic cells?
Peptidoglycan
How do the sizes of prokaryotic cells compare to eukaryotic cells?
Prokaryotic cells are much smaller
What is the approximate size of many prokaryotic cells?
~ 1 µm
What is the primary function of nerve cells (neurones)?
Conduction of electrical impulses
Nerve cells coordinate information from the brain and spinal cord with the rest of the body.
What structural feature of nerve cells allows them to conduct nerve impulses between different areas of the body?
Nerve cells are long
The elongated structure facilitates the coordination of information.
What are the extensions of the cytoplasm in nerve cells called?
Dendrites
Dendrites allow nerve cells to communicate with other nerve cells, muscles, and glands.
What is the purpose of the fatty sheath covering the axon in nerve cells?
Speeds up nerve impulse transmission
This feature enhances the efficiency of communication in the nervous system.
True or False: Nerve cells have a short structure that limits their ability to conduct impulses.
False
Nerve cells have an elongated structure that aids in impulse conduction.
What do muscle cells contain that allows them to contract?
Layers of fibres
Muscle cells are specialized to enable contraction for movement.
What is the primary function of muscle cells?
Contraction for movement
This function is essential for various bodily movements.
What special feature aids muscle cells in their function?
Many mitochondria
Mitochondria release energy necessary for contraction.
What do all muscle cells contain that facilitates contraction?
Protein filaments
These filaments can slide over each other to enable muscle contraction.
What is a root hair?
An extension of the cytoplasm, increasing the surface area of the cell in contact with the soil
What is the main function of root hairs?
Absorption of water and mineral ions from soil
How do root hairs increase the rate of water uptake?
By increasing surface area (SA) for greater osmosis
What is a special feature of root hair cell walls?
Thinner walls than other plant cells
Why do root hairs have thinner walls?
To allow water to move through easily due to shorter diffusion distance
What role do mitochondria play in root hairs?
Release energy for active transport of mineral ions
Fill in the blank: Root hairs increase _______ to maximize absorption.
surface area
True or False: Root hairs are thicker than other plant cells.
False
What happens to xylem cells to form a continuous tube?
Xylem cells lose their top and bottom walls.
What is the primary function of xylem cells?
Transport of water and dissolved ions.
What special feature of xylem cells allows for the continuous transport of water?
No walls between cells form continuous hollow tubes.
What do xylem cells lack that aids in the free passage of water?
Cells contain no organelles or cytoplasm.
What substance thickens the outer walls of xylem cells?
Lignin.
What is the role of lignin in xylem cells?
Strengthening the tubes and providing support for the plant.
Fill in the blank: Xylem cells form continuous hollow tubes through which water is drawn upwards towards the _______.
leaves
What is the primary function of phloem cells?
Transport of dissolved sugars and amino acids
Phloem is a type of tissue in vascular plants responsible for the transport of nutrients.
What special feature of phloem cells aids in the transport of materials?
Cells are joined end-to-end and contain holes in the end cell walls (sieve plates)
Sieve plates facilitate the flow of sugars and amino acids through the phloem.
How do the subcellular structures of phloem cells contribute to their function?
Cells have very few subcellular structures to aid the flow of materials
This adaptation allows for easier movement of dissolved substances.
Fill in the blank: Phloem cells transport _______ and amino acids.
dissolved sugars
What is a key advantage of electron microscopes over light microscopes?
Much higher magnification and resolving power
This allows for detailed study of cells and subcellular structures.
What subcellular structure can be studied in finer detail using an electron microscope?
Mitochondrion
Electron microscopes enable observation of various subcellular structures.
What has the use of electron microscopes helped biologists understand better?
The structure of the nucleus and cell membrane
Electron microscopy provides insights into cellular components.
What process allows bacteria in the agar to multiply?
Binary fission
What visible signs indicate bacterial growth in agar?
Agar darkening or colonies appearing
Fill in the blank: Incubating the plates allows the bacteria in the agar to multiply by _______.
binary fission
True or False: Incubating plates does not affect the growth of bacteria.
False
What is mitosis?
Mitosis is a stage in the cell cycle when the nucleus divides
Mitosis is essential for cell division and growth.
What is the cell cycle?
The cell cycle is a series of stages in the life cycle of a cell
It includes phases such as growth, DNA replication, and mitosis.
What happens during the growth phase of the cell cycle?
The genetic material of the cell (chromosomes) is doubled
This doubling is crucial for ensuring each daughter cell has the correct amount of DNA.
What are chromatids?
Each strand of a duplicated chromosome, initially attached to its identical copy
Chromatids are separated during mitosis.
What occurs to chromatids during cell division?
They are divided between the two genetically identical daughter cells
This ensures that each daughter cell receives an identical set of chromosomes.
What happens to subcellular structures during the growth phase?
The number of subcellular structures (such as ribosomes and mitochondria) increases
This increase supports the cell’s metabolic needs and prepares for division.
