Unit 1: Homeostasis, Cell structure Flashcards
Describe Prokaryotic Cells
No nucleus, few organelles, lack of internal membranes
Simple, primitive cells
(i.e., Bacteria)
Describe Eukaryotic Cells
Complex cells
- Has nucleus, with many organelles and an internal membrane.
- Each organelle has a specific function.
- More efficient than prokaryotic cells as chemical reactions occur in the specialized areas, not all over the cytoplasm.
(i. e., Animals, Plants, fungi, etc)
Plant cells vs Animal cells
Plant: Cell wall, one central vacuole, chloroplasts, no centrosome nor lysosome
Animal: No cell wall, many small vacuoles, no chloroplasts, centrosome and lysosome both exist
Structure & Function: Nucleus
Structure: Largest organelle, surrounded by double-layered membrane called the nuclear envelope, membrane has pores where molecules pass through called the nuclear pores
Function: The Control Center, governs all cellular activities
Function of Nucleolus
Where ribosomal RNA (rRNA) is produced/stored.
rRNA joins with protein to form ribosomal subunits, eventually forming ribosomes
Chromatin & Chromosomes
Chromatin is the hereditary material found in nucleus
Provides instruction to the organelles
Chromatin coils up into short rods to form chromosomes during cell division
Cytoplasm function and structure
Colloidal (small particles mixed evenly with another substance) substance that changes from liquid to solid
Contains and supports organelles
Cell membrane basic structure and function
Made up of proteins and phospholipids
The Barrier
- Controls movement of specific materials in and out of cell
- Provides rigidity and structure to cell
Cell wall
Only plant cells, additional protection with the cell membrane
Endoplasmic reticulum (Smooth vs Rough, function & structure)
System of flattened tubes, sacs, or canals. Sections of ER can break off vesicles in the process of blebbing.
Smooth ER: No ribosomes, manufactures lipids and contains enzymes to detoxify toxins
Rough ER: Has ribosomes which are sites of protein synthesis
Golgi Body function
The center of modification, storage, sorting and shipping of materials
- Receives protein or lipid filled vesicles from the ER
- Modifies and packages the vesicles
- From here they transport to different locations in and out of the cell
Vacuoles and Vesicles function
Vacuoles: More prominent in plant cells, storing water, nutrients, and wastes
Vesicles: Small vacuoles; transport vesicles move materials from organelle to organelle while secretory vesicles move materials from Golgi Body - cell membrane
Lysosomes function
Double membrane, special vacuoles formed by Golgi Body
Contains hydrolytic enzymes for digesting various materials in the cells. Fuses with vesicles entering the cell while also recycling old cell parts in a process called auto-digestion
Mitochondria function and structure (also the cellular respiration equation)
Double membrane organelle
-Inner membrane loops back and forth to increase its surface area. The inner space is called the matrix while the folds of the membrane are called the cristae.
- Uses carbohydrate and oxygen to from ATP, energy needed for cellular processes, while giving off carbon dioxide and water. This is called cellular respiration, described by the formula: C6H12O6 + 6O2 → 6CO2 + 6H2O + Energy
- The matrix contains the DNA, ribosomes, and enzymes that break down the carbs, while the cristae accommodates all the participants that are necessary for cellular respiration
Chloroplasts function (photosynthesis equation)
Found only in plant cells
Uses solar energy along with water & CO2 to produce glucose (carb)
Has a mutualistic relationship with the mitochondria. Uses CO2 and water produced by mitochondria to in turn produce carbs and oxygen that the mitochondria uses
The process is called photosynthesis, by the equation: 6CO2 + 6H2O + light energy → C6H12O6 + 6O2
Cytoskeleton function
Maintains cell shape, anchors the organelles and allows them to move when appropriate
Also allows cell movement, due to an interconnected system of microfilaments and microtubules
Cilia & Flagella function
Microtubules that project out of cells but bounded by the cell membrane
- Cilia: short and hair-like, used for movement by unicellular organisms
- Flagella: Longer than cilia, also for movement
Centrioles function
Found only in animal cells, two short cylinders of microtubules lying at right angles
Part of the centrosome, which is the major organizing centre of microtubules
Has a role in cell division, as well as giving rise to basal bodies that organize cilia and flagella.
How does cell size relate to its efficiency?
Adequate surface area is required for the cell to do any type of cellular activities.
The smaller the cell, the ratio of its surface area compared to its volume is bigger than the bigger cells.
Volume = the needs of the cell; bigger the cell, the more nutrients it requires and the more waste it produces
Thus, smaller cells are more efficient and cells have modifications such as folding and flattening to increase its surface area
What is the path of protein secretion? (7 steps)
- Protein is manufactured at ribosomes on rough ER
- Moves into the lumen of rough ER for modification
- Moves through the lumen to the outer edges, and encloses in transport vesicles by blebbing
- Transport vesicles move to the Golgi body and fuse
- Golgi body modifies, sorts, stores, and packages again for transport
- Golgi body packages the protein in secretory vesicles, as it blebbs off the Golgi body
- Secretory vesicles move and fuse with the cell membrane -> SECRETION!
Rough ER & Golgi body partnership
rough ER synthesizes and packages proteins for Golgi Body (transport vesicles) Golgi body further modifies, sorted and packaged for export (secretory vesicles)
Nucleolus & ribosomes partnership
nucleolus produces rRNA which forms ribosomal subunits which travel to cytoplasm and forms ribosomes
Vesicles & Golgi body partnership
Golgi body receives transport vesicles, modifies the contents and repackages into secretory vesicles
Cell membrane & lysosomes partnership
materials enter the cell through cell membrane in vesicles, lysosomes fuse with vesicle to digest its content
Chloroplasts & Mitochondria partnership
Chloroplasts produce carbohydrate through photosynthesis which in turn the mitochondria can use to make ATP
Centrioles & Cilia/flagella partnership
Centrioles give rise to basal bodies which organize cilia/flagella
What is homeostasis? (Sensor? Control center)
The tendency to maintain a stable, relatively constant internal state of body. (i.e., body temp, pH blood levels, etc)
This mechanism always consists of two parts: the sensor and the control center.
When a stimulus that affects the internal state occurs, the sensor detects and alerts the control center. Then, the control center causes an action to bring the conditions back to normal.
What is negative feedback? (explain with example on exercise)
An action to achieve homeostasis
To bring your internal state back to normal, your body usually does something to OPPOSE the stimuli that caused the disruption. It is the opposing nature that these actions are called negative feedback.
i.e., when you exercise, your body temperature goes up. Your body will start producing sweat, blood flows to your skin to increase heat loss, etc, to bring the temperature back up.
What is positive feedback? How is it different from negative feedback?
When your body does something that is in the same direction as the stimulus.
Can be dangerous (if you have a high fever, a positive feedback pushes the fever even higher)
Positive feedback helps the body cope with intermittent events (childbirth, blood clotting, etc) while negative feedback helps the body maintain homeostasis.
