Cells Flashcards
What is a cell?
the functional basic unit of life.
It is the smallest unit of life that is classified as a living thing, and is often called the building block of life.
What does unicellular mean?
consisting of one single cell.
What does multicellular mean?
consisting of more than one cell.
How many cells does a human usually have?
about 100 trillion or 10^14 cells;
What are the two types of cells?
prokaryote and eukaryote
Describe prokaryote cells:
usually independent,
simpler, and therefore smaller, than a eukaryote cell, lacking a nucleus and most of the other organelles of eukaryotes.
There are two kinds of these cells: bacteria and archaea; these share a similar structure
Describe eukaryote cells:
often found in multicellular organisms.
15 times wider than a typical prokaryote and can be as much as 1000 times greater in volume.
contain membrane-bound compartments in which specific metabolic activities take place.
Why do plants have large vacuoles
to store water and help it stay upright
Typical Cellular Organelles (structures living in a cell)
– Cell membrane – Cell wall – Mitochondrion – Nucleus – Chloroplast – vacuole
The mitochondrion is:
Known as the power house of the cell as it is responsible for the production of energy thru cellular respiration. It is enclosed by a thin membranous sac with inner partitions known as cristae
Cell Membrane
controls the passage of cellular material in and out of the cell with the use of a double layer of fat and protein which acts as selectively permeable barrier (allows liquids and gases to pass through)
Cell wall
Made up of the complex carbohydrate cellulose which helps to protect the cell and offer structural support. Found only in plant cells
Nucleus
The “brain” of the cell. Controls cellular activity as it stores the organisms hereditary information on densely. packed genetic material made up of DNA and protein called chromatin. Directs protein synthesis
Chloroplast
Found in plant cells only and is responsible for the plants autotrophic qualities. Contains the green pigment chlorophyll which harnesses the energy from sunlight and uses it to power photosynthesis
Vacuoles
essentially enclosed compartments filled with water containing inorganic and organic molecules including enzymes in solution.
Formed by the fusion of multiple membrane vesicles and are effectively just larger forms of these. The organelle has no basic shape or size, its structure varies according to the needs of the cell.
Help in Isolating materials that might be harmful or a threat to the cell and in cellular waste management. In plants they are large and few while in animals they are small and numerous
Endoplasmic Reticulum
The endoplasmic reticulum (ER) is an eukaryotic organelle that forms an interconnected network of tubules, vesicles, and cisternae within cells.
Rough endoplasmic reticulums synthesize proteins, while smooth endoplasmic reticulums synthesize lipids and steroids, metabolize carbohydrates and steroids, and regulate calcium concentration, drug detoxification, and attachment of receptors on cell membrane proteins.
Golgi Apparatus
The primary function of the Golgi apparatus is to process
and package macromolecules, such as proteins and lipids, after their synthesis and before they make their way to their destination; it is particularly important in the processing of proteins for secretion. The Golgi apparatus forms a part of the cellular endomembrane system.
Differences between Animal and Plant Cells
Animal Cells - Plant Cells
Usually smaller - Usually larger
No cell wall - A cell wall made of cellulose
Cytoplasm denser and more granular - Cytoplasm not so dense
Cytoplasm fills almost entire cell - only a thin lining of. cytoplasm
Vacuoles are small and temporary - Vacuoles prominent, one or more
Do not contain plastids - Usually contain plastids
Centrosome is present - Centrosome is not present
Cell Specialisation
The primary function of the Golgi apparatus is to process and package macromolecules, such as proteins and lipids, after their synthesis and before they make their way to their destination; it is particularly important in the processing of proteins for secretion.
The Golgi apparatus forms a part of the cellular endomembrane system.
Red Blood Cells
Red blood cells biconcave disc-like shape affords it increase surface area which results in increase oxygen carrying capacity. The opposite is observed with sickled cell on the left. Patients can become anaemic and suffer from shortness of breath due to the decreased oxygen carrying capacity of each cell.
Nerve Cell
Nerve cell functions to receive, conduct and. transmit electrical impulses. The out-reaching dendrites enable maximum interaction with surrounding neurons. The thin myelinated axons allow for accurate transmissions.
Diffusion
a process of passive transport in which molecules move from an area of higher concentration to one of lower concentration
Osmosis
the movement of water across a membrane from an area of low solute concentration to an area of high solute concentration passing through a selectively permeable membrane
Hypertonic Solution
solution has a higher solute (dissolved substance) concentration than the cell does.
has a lower concentration of water than the cell does.
Cell membranes and plant cell walls are semipermeable barriers, which means that certain molecules can diffuse through them, while other molecules can not.
Hypotonic Solution
has a lower solute concentration than the cell does. As a result, it also has a higher concentration of water than the cell does.
Osmosis draws water out of the solution and
into the cells. As a result, plant and animal cells
both appear more plump when placed in a
hypotonic solution.
Isotonic Solution
has the same solute concentration,
and thus the same water concentration, as the
cells do.
there would not be a concentration gradient
since a gradient by definition involves a
difference.
