Unit 1 Topic 1 Cells as the basis of life Flashcards
State the cell theory
All organisms are composed of one or more cells.
All cells come from pre-existing cells.
The cell is the smallest structural and functional unit of life
Describe differences between a prokaryotic cell and a eukaryotic cell.
A prokaryotic cell lacks nucleus and other membrane-bound organelles, whereas a eukaryotic cell contains nucleus and other membrane-bound organelles.
A prokaryotic cell contains plasmids, whereas a eukaryotic cell doesn’t.
A prokaryotic cell contains single, circular chromosome, whereas a eukaryotic cell contains multiple, linear chromosomes.
State the kingdoms that are part of the domain Eukarya.
Plantae, Animalia, Protista, Fungi
State features that are common in all cells.
Cell membrane
Cytoplasm
Ribosomes
DNA
The function of nucleus is:
Contains genetic information (DNA)
and controls cellular activities by coding for proteins.
The function of chloroplast is
Site of photosynthesis.
Produces glucose, which is a main source of cell’s energy.
The function of mitochondria is
Site of aerobic cellular respiration. (power generation)
Produces energy (in the form of ATP) to power cellular activities.
The function of rough endoplasmic reticulum is
Folds and modifies proteins.
the function of smooth endoplasmic reticulum is
Produces various molecules, such as lipids and steroids.
the function of Golgi apparatus is:
Modify and package proteins into secretory vesicles.
Further information: Secretory vesicles fuse with the cell membrane to release its proteins out of the cell in a process called exocytosis.
the function of lysosome is:
Break down any unwanted materials (e.g waste products, damaged organelles, etc).
the function of large permanent vacuole is
Storage of various chemicals needed in the plant cell.
Provides structural support.
the function of ribosome is
protein synthesis
State the different levels of organisation in a complex organism.
cell -> tissue -> organ -> body system -> organism
Cell specialisation means?
the process by which cells develop unique structures and functions to perform specific tasks in an organism.
The main function of cell membrane is
to separate the interior of the cell (cytoplasm) from the external environment so that its internal environment can be carefully regulated.
What are some of the commonly regulated aspects of the internal cellular environment?
Temperature
Oxygen concentration
CO2 concentration
pH
Osmotic pressure (conc. of salts or ions)
Nitrogen waste concentration
Glucose concentration
State the chemical properties of the phosphate head
Polar/hydrophilic
soluble in water
Lipophobic
State the chemical properties of the fatty acid tails
non-polar/hydrophobic
insoluble in water
Lipophilic
State the two components that make up a phospholipid.
Phosphate head
Fatty acid tails
State all the major components that make up the cell membrane
Phospholipid
Cholesterol
Protein
Carbohydrate
What does it mean by selectively permeable membrane?
The membrane allows some molecules to pass through but not all
Which groups of molecules can move through the phospholipid bilayer?
Small, polar
Small, non-polar
Which groups of molecules cannot move through the phospholipid bilayer?
Large, polar
Ions
Give two examples of small nonpolar molecules
Carbon dioxide, Oxygen (gas), steroid hormones
Give two examples of small polar molecules
water, urea
Give two examples of large polar molecules
glucose, amino acid
Give two examples of ions
Sodium ion (Na+), Calcium ion (Ca2+), Chloride Ion (Cl-)
What is the function of channel protein?
To allow specific ions to move in and out of the cell
What is the function of carrier protein?
To allow specific large polar molecules (e.g. glucose and amino acid) to move in and out of the cell.
Define diffusion.
The net movement of solute particles from an area of high concentration to an area of low concentration down along the concentration gradient.
This process is passive - doesn’t require energy.
What happens at the end of diffusion?
the concentrations are balanced, and the dynamic equilibrium is reached between the environments.
What factors influence the rate of diffusion and how?
1) Temperature.
The higher the temperature, the faster the rate of diffusion.
2) Concentration gradient.
The higher the difference in concentrations, the faster the rate of diffusion.
3) Particle size.
The smaller the particles (solutes), the faster the rate of diffusion.
Describe the movement of particles in active transport.
Particles move from an area of low concentration to an area of high concentration against the concentration gradient. This process requires energy (in the form of ATP).
Define osmosis.
The movement of water molecules from an area of high water concentration to an area of low water concentration.
This process is passive.
Describe an isotonic solution in relation to a cell.
the solution has the same solute concentration as the cell.
Describe a hypotonic solution in relation to a cell.
the solution has lower solute concentration than that of the cell.
Describe a hypertonic solution in relation to a cell.
the solution has higher solute concentration than that of the cell.
What happens to a red blood cell (animal cell) when it is placed in an isotonic solution?
The red blood cell’s volume remains the same, as there is dynamic equilibrium between the cytoplasm and outside of the cell.
What happens to a red blood cell (animal cell) when it is placed in a hypotonic solution?
The red blood cell’s volume starts to increase due to osmosis - water from outside of the cell (high water concentration) moves across the phospholipid bilayer and into the cytoplasm (low water concentration). This causes the cell to swell up and can eventually lead to cell lysis.
What happens to a red blood cell (animal cell) when it is placed in a hypertonic solution?
The red blood cell’s volume starts to decrease due to osmosis - water from the cytoplasm (high water concentration) moves across the phospholipid bilayer and into the hypertonic (low water concentration) external environment. This causes the cell to shrink and shrivel, making it crenated.
What happens to a plant cell when it is placed in a hypotonic solution?
The plant cell’s volume starts to increase due to osmosis - water from outside of the cell (high water concentration) moves across the phospholipid bilayer and into the cytoplasm (low water concentration). This causes the cell to become turgid, providing additional structural support to the plant.
What happens to a plant cell when it is placed in a hypertonic solution?
The plant cell’s volume starts to decrease due to osmosis - water from the cytoplasm (high water concentration) moves across the phospholipid bilayer and into the hypertonic (low water concentration) external environment. This causes the cell to become plasmolysed, and the plant is under severe stress.
What happens to a plant cell when it is placed in an isotonic solution?
The plant cell’s volume remains the same, as there is dynamic equilibrium between the cytoplasm and outside of the cell. However, this causes the cell to become flaccid, and the plant starts to show early signs of wilting.
Define exocytosis.
The bulk export of substances out of the cell (from cytoplasm to extracellular fluid). Requires a large amount of ATP to power this process.
Describe how seretory proteins are secreted out of the cell via exocytosis.
Secretory vesicles (from Golgi Apparatus) containing secretory proteins fuse with the cell membrane, thereby releasing its contents out of the cell.
Define endocytosis.
The bulk import of substances into the cell (from the extracellular fluid into the cytoplasm). Requires a large amount of ATP to power this process.
Define phagocytosis.
a type of endocytosis where the cell engulfs large solid(s).
Define pinocytosis.
a type of endocytosis where the cell engulfs a large amount of fluid.
Hypotonic solution can be described as low water concentration or high water concentration?
High water concentration.
Explanation: Hypotonic means low solute concentration. This means there is less things dissolved in the water -> High purity -> high water concentration.
Hypertonic solution can be described as low water concentration or high water concentration?
Low water concentration.
Explanation: Hypertonic means high solute concentration. This means there is more things dissolved in the water -> low purity -> low water concentration.
What are the two main characteristics of stem cells?
Self-renewal and Potency
What does it mean by self-renewal?
ability to go through several cycles of cell division without further differentiation.
What does it mean by potency?
ability to differentiate (change) into different cell types.
State the four levels of potency.
Totipotent, Pluripotent, Multipotent, Unipotent.
What does it mean by totipotent stem cells?
These stem cells can differentiate into any other cell types and give rise to a complete organism.
What does it mean by pluripotent stem cells?
These stem cells can differentiate into any other cell types except for the cell types that make up the placenta. As a result, these stem cells alone cannot form a complete organism.
What does it mean by multipotent stem cells?
These stem cells can become multiple, but limited cell types.
What does it mean by unipotent stem cells?
these stem cells can differentiate into only one cell type.
During which stage(s) of the embryonic development can we find totipotent stem cells?
Totipotent stem cells can be found from zygote to morula stage of the embryonic development.
During which stage of embryonic development can we find pluripotent stem cells?
Blastocyst stage - the inner cell mass inside the blastocyst is said to be pluripotent, as it can give rise to the three primary germ layers.
During which stage of embryonic development can we find multipotent stem cells?
Gastrula stage - each germ layer can give rise to multiple, but limited types of cells.
What are the three primary germ layers are called?
Ectoderm, Mesoderm and Endoderm
Ectoderm gives rise to which cell types in the body?
Skin and the cells of the nervous system (e.g. brain cells)
Endoderm gives rise to which cell types in the body?
the cells that form the digestive tract.
Mesoderm gives rise to which cell types in the body?
muscle and bone cells as well as blood cells.
