General Histology Flashcards
The four tenets to the cell theory are
- All organisms are composed of one or more cells
- The cell is the most basic structural unit of life - units smaller than cells are not alive
- Cells arise by division of pre-existing cells - spontaneous generation does not exist
- Cells can be cultured to produce more cells; in vitro (outside organism or cell) or in vivo (inside organism or cell)
The two main groups of cells are
- Prokaryotic cell
2. Eukaryotic cell
Functions of cells include:
- Biosynthesis - protein, lipids
- Movement - amoeboid locomotion,
internal transport - Absorption/Secretion - endocytosis, exocytosis
- Cell division - mitosis, meiosis
- Energy production
The human (eukaryotic cell) is composed of three basic parts, namely:
- Cell membrane
- Cytoplasm
- Nucleus
What is a cell
A cell is the basic, structural and functional unit of life. It is the smallest, basic structure of higher organisms capable of independent existence.
The major difference between eukaryotic and prokaryotic cells is
The eukaryotic cells have a true nucleus while prokaryotic cells do not have a nucleus but an undefined nuclear region made up of a single chromosome called nucleoid.
Membrane bound organelles include
- Mitochondria
- Nucleus
- Smooth and Rough endoplasmic reticulum
- Golgi apparatus
- Vesicles e.g Lysosomes, Phagosomes, Peroxisomes (microbodies)
Non-membrane bound organelles include
- Ribosome
- Cytoskeleton e.g Microfilaments, Microtubules
- Centriole (basal body)
What is mitosis
This is a type of cell division which involves the dividing of the genome (genetic material) between two daughter cells.
Meiosis is
This is a specialised type of cell division that occurs during the formation of gametes.
The protein which acts as a “surveillance system” to accept signals provoked by DNA damage and stimulates the halting of the DNA replication process is
p53
The endomembrane system is
This is defined as the set of membranes suspended in the cytoplasm of eukaryotic cells that form a single functional and developmental unit, either being connected together directly or exchanging material through vesicular transport.
The phases of mitosis and meiosis are
- Prophase
- Metaphase
- Anaphase
- Telophase
The position at which a gene is located on a chromosome is called
Locus
Differentiation is
This is the process by which an unspecialised cell becomes specialised into one of the many cells that make up the body such as heart, liver or muscle cell.
Three basic categories of cells that make up the mammalian body are:
- Germ cells
- Somatic cells
- Stem cells
What is DNA replication?
This is the process of duplicating a cell’s genome which is required every time a cell divides.
DNA transcription is
This refers to the synthesis of RNA from DNA template.
The process whereby RNA directs protein synthesis is called
Translation
DNA repair systems include:
- Photoreactivation
- Nucleotide excision repair
- Recombination repair
- Base excision repair
- Mismatch repair
- Adaptive/inducible repair
- SOS repair
What are caspases
These are biological enzymes which break down human cells into small fragments.
Apoptosis is
This is a form of programmed cell death which involves a sequence of micromorphological events that leads to the elimination of cells without releasing harmful substances into the surrounding area.
What is the difference between apoptosis and oncotic necrosis
- Apoptosis is energy dependent while oncotic necrosis is energy independent
- Apoptosis does not damage plasma(cell membrane) while Oncotic necrosis causes direct damage to plasma membrane
- Apoptosis usually requires sufficient availability of caspases while Oncotic necrosis requires decreased availability of caspases.
Describe the plasma membrane
The plasma membrane (which is a fluid mosaic model) is a lipid bilayer interspersed with proteins and carbohydrates (in a mosaic pattern) that separates the interior of the cell from the external environment.
What are the three types of lipids present in the plasma membrane?
- Phospolipids (most abundant)
- Cholesterol
- Glycolipids
State two functions of the plasma membrane
- It forms a barrier which is selectively permeable
2. It aids in cell-to- cell communication
What is the function of the mitochondria
ATP Synthesis
What is the function of ribosomes
Protein synthesis
The two types of Endoplasmic reticulum are:
- Rough (Granular) endoplasmic reticulum
2. Smooth (Agranular) endoplasmic reticulum
What’s the function of rough endoplasmic reticulum
Due to the ribosomes present on its outer surface making it rough, it is also involved in protein synthesis
What’s the function of smooth endoplasmic reticulum
Synthesis of lipids and steroid hormones
What’s the function of Golgi apparatus (complex)
Modifying, sorting and packaging of secretory products
What’s the function of Lysosomes
Intracellular digestion
What’s the function of the nucleus
It is considered the largest cell organelle and contains the genetic material of the cell.
All the organs of the human body are composed of four basic tissues, namely:
- Epithelial tissue
- Connective tissue
- Nervous tissue
- Muscle tissue
What is Epithelial tissue
Epithelial tissue is an aggregate of uninterrupted cells that covers the inner and outer surfaces of organs and body cavities.
