CELL STRUCTURE & FUNCTION Flashcards
Organization
Biological organisation is the hierarchy of complex biological structures and systems that define life using a reductionistic approach
Body’s largest organ system
Integumentary system, includes skin and its associated structures like hair and nails
Metabolism
The sum of all reactions that take place ensuring the organisms stays alive
2 types of metabolism for sustaining physiological functions:
- Anabolism: Combines simpler molecules into larger, more complex substances (eg. Amino acids combining to make proteins)
- Catabolism: Breaks down larger, more complex substances into smaller and simpler molecules (eg. Maltose broken down into two glucose)
Exchange of material
Organisms constantly interact with environment by exchanging materials. (eg. CO2 and glucose crossing the plasma membranes, food getting ingested, waste materials getting eliminated)
Responsiveness
Ability of an organism to adjust to changes in its internal and external environment (eg. Increased body temperature in humans will cause the production of sweat and the dilation of blood vessels to cool the body)
Movement
Human movement includes not only actions at the joint of the body, but also the motion of individual organs and individual cells
3 examples of movement in biological organization:
- Red and white blood cells move through blood vessels
- Muscle cells contract and relax to effect movement of body parts
- Unicellular organisms move substances in and out through the cell membrane
Development
All changes that the body goes through in life, including cell differentiation, growth, and repair
Growth
Increase in body size due to increase in cell size, cell number, or accumulation of non-cellular material
Reproduction
Formation of new organisms from parent organisms
Levels of structural organizations (6):
- Chemical level
- Cellular level
- Tissue level
- Organ level
- Organ system level
- Organismal level
Chemical level (3):
- Atom is the smallest and most fundamental unit of matter
- Molecule formed by at least two atoms held together by a chemical bond
- Important biological macromolecules (eg. Protein, carbohydrate, lipid, nucleic acid)
Cellular level (3):
- Organelles
- Cell itself is the fundamental unit of structure and function in living organisms
- Unicellular and multicellular cells
Organ
Anatomically distinct structure of body composed of two or more types of tissue
Organ system
Group of organs that work together to perform major functions or meet physiological needs of body
Organelles
“Little organ”; Membrane enclosed bodies in a cell that has unique functions - Think of organs in our body, but cells have organelles
Unicellular cell
Organisms composed of a single cell (eg. Bacteria, amoeba, paramecium, yeast)
Multicellular cel
Organisms composed of many cells (plants, animals)
Eukaryotic cell
Organisms whose cells contain a nucleus and other membrane bound organelles
Prokaryotic cell
Organisms that don’t contain any membrane bound organelles and are always part of unicellular organisms
Tissue & organ level (2):
- Cells combine to form tissues
- Collection of tissues that share a larger common function are called organs
Tissue
Groups of similar cells working together to carry out the same function
Examples of some tissues in animals (4):
- Muscle tissue
- Nervous tissue
- Epithelial tissue
- Connective tissue
Example of some tissues in plants (3):
- Dermal tissue
- Vascular tissue
- Ground tissue
Organ
Collection of tissues that share a larger common function
Examples of some organs in animals (5):
- Liver
- Kidney
- Stomach
- Brain
- Heart
Examples of some organs in plants (3):
- Root
- Stem
- Leaves
Organisms
Individual living entities that may be unicellular (bacteria) or multicellular (tree)
What do all living cells in a multicellular organism contain
An internal cytoplasmic compartment, composed of cytosol and organelles
Cytosol
Jelly like substance within the cell that provides a water-based fluid necessary for biochemical reactions
Cell membrane function
Separates the internal contents of the cell from the extracellular environment and regulates passage of some substances in and out of cell
Cell membrane structure
Composed of a phospholipid bilayer with embedded proteins. The phospholipids form a bilayer that provides a selectively permeable barrier
Selectively permeable barrier
Where some molecules and compounds pass easily through the membrane, while others are prevented from passing at all
Cytoplasm and function
Comprises the contents of a cell between the plasma membrane and the nuclear membrane. Provides platform upon which other organelles ca operate within the cell
Cytoplasm structure
Composed of organelles suspended in a gel-like cytosol. Cytoplasm is 70-80% water but it has a semi-solid consistency due to the proteins
Endomembrane system
Group of membranes and organelles in eukaryotic cells that work together to modify, package, and transport lipids and proteins
What do the organelles in the endomembrane system consist of (5):
- Endoplasmic reticulum
- Golgi Apparatus
- Lysosome
- Vesicles
- Cell membrane
Endoplasmic reticulum (ER)
Series of interconnected membranous tubules involved in protein synthesis and lipid metabolism
Rough ER function
Continuous with the nuclear envelope, studded with millions of membrane bound ribosomes and has flattened membranes. It is involved with the production, folding, quality control and despatch of some proteins
Smooth ER function
Synthesizes carbohydrates and lipids. Involved in the detoxification of medications and poisons, alcohol metabolism, and storage of calcium ions
What happens to modified proteins and phospholipids
The modified proteins and phospholipids are packed into transport vesicles fuse Golgi Apparatus
Golgi apparatus structure
Contains a cis face (facing the ER) and a trans face (facing the cell membrane). Proteins and lipids from the ER enter golgi at cis face and exit at trans face
Golgi Apparatus function
Functions as a factory in which proteins and lipids are packaged and further processed and get “tagged” with molecules to enable them to be routed to proper destinations
2 main ways that cells can leave the golgi appartus
Some leave in transport vesicles that deposit the contents into other parts of the cell, and some leave in secretory vesicles that fuse with the plasma membrane and release their contents OUTSIDE cell
Transport vesicles
Takes proteins/lipids to where they need to go in cell
Secretory vesicles
Will take the proteins/lipids to cell membrane to exit the cell
Lysosome function (2):
- Contains digestive enzymes that break down and digest unneeded cellular components, such as damaged organelle in a process called autophagy (self eating)
- Destroy pathogenic organisms that might enter cell
Phagocytosis
“Cell eating” - engulf
Autolysis
“Self destruct” mechanism and makes process of cell death controlled
How are vesicles formed
When the membrane bulges out and pinches off
Vesicles
Membrane-bound sacs that function in transport and can also fuse with other membranes within the cell system
Vesicles fusing (2):
- Vesicles produced by the rough ER will travel to an fuse with the golgi apparatus
- Vesicles produced by the golgi apparatus will travel to and fuse with the cell membrane
Ribosomes
Cellular structures responsible for the synthesis for proteins and consists of a large and small subunit made and assembled in the NUCLEUS and transported to CYTOPLASM where the final ribosome is assembled. They can also be found bound to either the cytoplasmic side of the plasma membrane or the cytoplasmic side of the ER
Free ribosomes
Float in the cytoplasm as single structures or clustered
Mitochondria
Responsible for making ATP in the breakdown of glucose during cellular respiration
Mitochondria structure
Oval shaped, double membrane bound organelles that have their own ribosomes and DNA
Cristae
Inner membrane folds in mitochondria
Matrix
Semi fluid inside the mitochondrion
Nucleus
Most prominent organelle and is the control center of cell because it houses the cell’s DNA in the form of chromatin and directs the synthesis of ribosomes and proteins. Nucleus sends commands to cells via molecular messengers
Nuclear envelope
Double membrane structure of nucleus containing nuclear pores to control passage in and out of nucleus and continuous with the ER
Nucleoplasm
Semi-fluid substance in the nucleus, the chromatin, and the nucleolus
Chromosome
Linear piece of DNA associated with various proteins
Chromatin
Combination of DNA and proteins in chromosomes
Example of a cell without a nuclei
Red blood cells
Cell division
Part of a larger sequence of events called the cell cycle, which generates two new cells as cells must replace themselves over the lifetime of a person
What cells do not undergo cell division (4):
- Red blood cells
- Most neurons
- Some muscle cells
- Gametes
Somatic cell
General term for a body cell except for the cells that produce eggs and sperm (germ cells)
Cell growth
Once cells divide, they grow and increase in size (eg. Nerve cells appearing as small cells but then elongate to become long, or muscle cells growing long as muscles form)
Cell differentiation
Process by which unspecialized cells (stem cells) become specialized to carry out distinct functions within the body. It is important because it leads cells to assume their final morphology and physiology
Stem cell
Cells with the potential to develop into many different types of cells in the body. They are unique because it can continually divide and regenerate new stem cells instead of further specializing
Example of stem cells (3):
- Embryonic stem cells of embryo
- Fetal stem cells of fetus
- Adult stem cells for adults
Cell specialization
As cells specialize, they make undertake major changes in size, shape, activity and overall function
Muscle fibres (cell specialization)
Long-slender structures that are well suited to contracting to produce movement
Neurons/nerve cell (cell specialization)
Exceptionally long and thin to transmit information
Erythrocytes/red blood cells (cell specialization)
Used to transport oxygen in blood. They are tiny in size and the lack of nucleus make them well suited to squeeze through capillaries and lack of mitochondria means they do not use up the oxygen they deliver to cells
Leukocytes/white blood cells (cell specialization)
Larger than erythrocytes/red blood cells which allow them to engulf large particles or whole cells
Nucleolus
Where ribosome subunits are produced
