Biology Chapter 8 Cells Flashcards
(45 cards)
1
Q
What is a cell?
A
- The basic units of life.
- Surrounded by a plasma membrane (cell membrane) that separates the inside of the cell and the outside of the cell
- Highly organized structures
- The site of many chemical processes and reactions
- Able to sense and respond to changes in their environment. (Monitoring internally and externally)
- Has the potential to survive on its own.
2
Q
Cell Theory
A
- All known living things are made up of cells
- The cell is the basic unit of structure, physiology, and organization in living things.
The correct interpretation of cell formation by division was finally expressed by Rudolph Virchow
“All cells only arise from pre-existing cells”
3
Q
Prokaryotes
A
- Simplest type, unicellular
- Cytoplasm = cytosol + suspended materials including organelles
- No nuclear envelope
- No membrane bound organelles except ribosomes
- DNA in a region called nucleoid, small circular DNA called plasmids present.
4
Q
Eukaryotes
A
- Includes Protists, Animal, Plant and Fungi
- DNA is housed in the Nucleus in the form of chromosomes
- Contain membrane-bound organelles
- Organelle membranes fold and stack within the organelle in order to maximize surface area for reactions to occur.
- This enables hundreds of different chemical reactions to occur at the same time without interference.
5
Q
Similarites of Eukaryotes and Prokaryotes
A
Prokaryotes and eukaryotes both have cell membranes, genetic material (DNA), and ribosomes for protein synthesis. Additionally, they both engage in metabolic processes to generate energy and can reproduce.
- Chromosones
- DNA as genetic material
- Ribosomes
- Cytoplasm
- Plasma Membrane
- Sometimes have cell walls
- Vacuoles
6
Q
Differences of Eukaryotes and Prokaryotes: Prokaryotes
A
Prokaryotes
- Nucleoid
- Circular DNA that floats freely around the cell
- Simpler DNA
- No membrane bound organelles
- Divide by Binary Fission
- Typically unicellular
- Anaerobic and aerobic
7
Q
Differences of Eukaryotes and Prokaryotes: Eukaryotes
A
- Eukaryotes
- Nucleus
- Linear DNA that is held in the nucleus
- Complex DNA
- Membrane bound organelles
- Typically much larger
- Divide by mitosis and meiosis
- Typically multicellular
- Aerobic
8
Q
What is a plant cell (characteristics)
A
- Plant cells are characterised by the following unique features:
- Strong cell walls made of cellulose
- Contain organelles called chloroplasts which allow the plant to undergo photosynthesis.
- They have a large permanent vacuole which stores various chemicals.
- There is inwards pressure from the outerwall and inner wall to keep the plant cell rigid
- Water is lost from the vacuole
9
Q
Animal Cells
A
- Animal cells are characterised by:
- No cell wall, only a relatively thin cell membrane
- Do not contain large vacuoles, Chloroplasts and do not undergo photosynthesis.
10
Q
Fungal Cells
A
- Like plants, fungi cells are surrounded by a Cell Wall.
- However, it is made of a carbohydrate called Chitin.
- They may be unicellular like yeast to multicellular like mushroom.
- Do not contain chloroplasts and do not undergo photosynthesis.
- Body thread called hypha which are septate or aseptate.
- Network of hyphae - mycelium
11
Q
Protists
A
- Single-celled organisms
- Mostly microscopic but some can reach cant sizes like the kelps
- They also may be heterotrophic or photosynthesize like a plant.
- Unicellular or multicellular
- They all prefer aquatic or moist environments
12
Q
Cytoplasm
A
- The cytoplasm is a thick fluid between the cell membrane
and the nucleus - Consists of organelles suspended in cytosol.
- The term protoplasm refers to the nucleus and cytoplasm
together.
13
Q
Cytosol
A
- The liquid part of the cytoplasm
- Made up from a mixture of substances
14
Q
Cell Membrane
A
- Surrounds the cell and separates the cell contents from the external environment
- Controls what enters and leaves the cell
15
Q
Nucleus
A
- Controls all activites of cell
- Contains genetic material (DNA and RNA)
- When the cell is not dividing DNA, it is in the form of long strands called chromatin (e.g unwind strands of wool)
- When the cell is dividing the chromitn thickens coil to form chromosones
16
Q
Nucleolus
A
- This is an area within the nucleus
- It is composed of RNA which has a role in protein synthesis
17
Q
Nuclear Membrane
A
- This separates the nucleus from the cytoplasm
- It has two membranes
- There are gaps in the nuclear membrane called nuclear pores
- The nuclear pores allow substances to enter and leave the nucleus
18
Q
Ribosomes
A
- Small, spherical organelles
- Where amino acids are joined together in a sequence determined by the code in DNA molecules (protein synthesis)
- Ribosomes can be free in the cytoplasm or attached to endoplasmic reticulum
19
Q
Endoplasmic reticulum
A
- Network of channels of parallel membranes
- Provides a surface for chemical reactions
- Channels used for storing or transporting molecules
- If ribosomes are attached to the ER; they are called rough ER
- If ribosomes are not attached; they are called smooth ER
20
Q
Golgi Apparatus
A
- Series of flattened membranous bags stacked one upon the other
- Often near the nucleus
- Its function is to modify proteins and to package them for secretion
- At edges of membranous bags, the membrane pinches off to form a vesicle
- Vesicles migrate to the cell membrane where proteins leave the cell by exocytosis
21
Q
Lysosomes
A
- Small spheres formed from the Golgi apparatus
- Contains digestive enzymes
- When particles or liquids are taken into a cell by endocytosis, they form vesicles in the cytoplasm
- Lysosomes fuse with these vesicles and digestive enzymes within lysosomes break down material inside the vesicle
22
Q
Mitochondria
A
- The powerhouse of the cell
- Where cellular respiratio occurs
- Double membrane structures
- Spread throughout the cytoplasm
- Cellular reactions that release energy
- Folding of the inner membrane increases the surface area
23
Q
Centrioles
A
- ## Cylindrical structure – a ring of fine tubules
24
Q
Other organelles
A
- Plastids – plant cells only. Three types, including chloroplasts
- Vacuoles – storage structures, prominent in plant and unicellular
animals
25
What does a cell require to do work?
A cell needs energy to do various types of work; chemical, mechanical and electrochemical work.
- Chemical work
- Building
- Arranging
- Breaking apart substances
- Staying alive
- Mechanical Work
- Moving
- Electrochemical Work
- Moving charged substances across membranes
26
How does a cell get energy?
Plant cells get their energy from photosynthesis
- Energy is created by photosynthesis, light energy is converted into chemical energy.
Carbon Dioxide + Water -> Glucose + Oxygen
For animal cells, they get their energy from cellular respiration.
- Glucose + Oxygen → Carbon Dioxide + Water
We can also get energy when we eat carbohydrates.
- Digestion breaks these complex sugars down to glucose
- Glucose, a high energy molecule, is absorbed across the gut into your bloodstream
- Glucose in the cell is the beginning of metabolism
27
Why does the cell need water and how does it get it?
- Provides an environment for metabolic reactions to occur
- Acts as a mode of transport by providing a solution for elements to be dissolved in
- Plants require water for photosynthesis
- The cell gets water by osmosis, a passive (not using energy) process
- Water travels on a concentration gradient (high to low concentration of osmosis)
- Water is also produced as the end product of cell respiration
28
Why is carbon dioxide needed
- Oxygen is necessary in cells for cellular respiration which is the production of energy cell
- In plants cells carbon dioxide is needed to carry out the process of photosynthesis
- Energy is needed for life-sustaining
- Oxygen enters the blood stream through the lungs
- Oxygen goes into cells from the blood
- Carbon Dioxide is toxic for us
- In plants, absorbed through the stomata from air outside
- In single celled organisms, these gases enter and leave cells by diffusion - the passive movement of molecules from areas of high concentration to low concentration
29
What are biomacromolecules
- A large, organic molecule such as carbohydrates, lipids, proteins, and nucleic acids.
- Lipids e.g. Triglyceride
- Nucliec Acids e.g. DNA
- Carbohydrates e.g. Starch is a storage component
- Protein e.g. Enzymes
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Carbohydrates
- Carbohydrates are biological molecules made of carbon, hydrogen, and oxygen in a ratio of roughly one carbon atom to one water molecule
- Carbohydrate chains come in different lengths, and biologically important carbohydrates belong to three categories: monosaccharides, disaccharides, and polysaccharides.
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Proteins
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Lipids
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Nucleic Acid
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Cell Plasma Membrane
The cell plasma membrane is like a protective skin around a cell. It controls what goes in and out of the cell like a gatekeeper. This membrane is made up of fats (lipids) and proteins, and it’s flexible so the cell can change shape if needed. It keeps the cell safe by letting in the good stuff (like nutrients) and keeping out harmful things. It also helps the cell communicate with other cells by sending and receiving signals. So, in simple terms, it’s the cell’s protective, controlling, and communicating outer layer.
35
Fluid Mosiac Model
- The membrane is a phospholipid bilayer
- Proteins and other molecules are embedded in the membrane
- The phospholipids are shaped similarly to a head and tail
- The heads like water (hydrophilic), and the tails don’t like water (hydrophobic)
- The tails bump against each other, and the heads are out facing the watery area surrounding the cell. The two layers of cells are called the bi-layer.
- You’re going to find cholesterol scattered around the cell membrane region
- They help with maintaining the rigid and fluid structure of the phospholipid
36
Membrane proteins
- A variety of proteins are embedded in the bi-layer
- These serve various functions including the movement of substances in and out of the cell (membrane transport proteins)
- Some act as receptor sites for hormones
37
Membrane transport protein
- Membrane proteins that aid the movement of substances in and out of the cell include:
- Channel proteins (ion channels) - open channels that allow facilitated diffusion
- Carrier proteins that allow facilitated diffusion (e.g. glucose) and active transport (specific membrane pumps)
38
Endocytosis
Think of it like the cell “eating” or “swallowing” something. The cell wraps around a substance, like a nutrient or a small particle, and pulls it inside. This way, the cell can bring in the things it needs to survive.
Example: Imagine you’re taking a bite of food. Your mouth (the cell) wraps around the food and pulls it in.
39
Exocytosis
This is the opposite of endocytosis. The cell “spits out” or releases something. It packages up waste or important molecules (like hormones) in little bubbles called vesicles and then pushes them out of the cell.
Example: It’s like when you chew gum and then spit it out. The cell gets rid of stuff it doesn’t need anymore or sends out important signals to other cells.
40
Osmosis
The movement of water through a plasma membrane from a high concentration to a low concentration
41
Facilitated diffusion
- Only difference between diffusion and Facilitated diffusion is that they have something assisting their movement through a channel protein or carrier protein within the plasma membrane of a cell.
- The movement goes down the concentration gradient
42
Simple Diffusion
- Movements of particles from a high concentration to a low concentration
- Diffusion talks about molecules in general
43
Hypertonic solution
- Solute concentration is high outside of the cell and low inside of the cell
- The cell will then lose water and the water will exit the inside of the cell
- When a cell is in a hypertonic solution, it will shrivel up (Plasmolyzed cell)
- Once it is hydrated, it will be fixed
44
Hypotonic solution
- Low solute concentration on the outside, high concentration on the outside
- Water will come into the cell
- This happens when you try repair a cell hypertonic state
- Cells swell and eventually burst, once it ruptured, you cannot fix it
- Turgid Cell
45
Isotonic solution
- Solute inside the cell is equal to the solute out of the cell
- Not necessary to move water in and out of the cell
- This is normal (Flacid)
- The Isotonic state is the ideal state a cell should mean
