(Unit 4) Ch. 4 Flashcards
What is the important emergent property within cells?
Life; it only exists when biomolecules and chemistry are organized into a cell.
Define “Cell”
Smallest unit of living matter
What is Cell Theory?
- All organisms are composed of ONE OR MORE cells (accounts for unicellular organisms)
- Cells are the basic units of structure and function (and therefore life) in organisms (no spontaneous generation)
- Cells come only from pre-existing cells because cells are self-reproducing
Describe the basic difference in reproduction/growth between single-celled organisms and multicellular organisms.
Single Cell- Reproduces- Divides and becomes two new organisms
Multicellular- Grows- Many cells divide
What do all cells have that allow them to support Life? How are they related?
Structure and Function- Structure allows for function and function requires structure
According to FCPS, what are the Characteristics of Life?
HOG RACER (+D) maintain Homeostasis highly Organized Grow and Develop Reproduce Adapt and Evolve made of Cells obtain and use Energy Respond to environmental stimuli
Have DNA (may change in future)
What is the difference between Growth and Development?
Growth- Get’s bigger (refers to size)
Develop- Changing in organization
What is Homeostasis and what is it an example of?
Example of response to environmental stimuli and it means it maintains a constant internal environment despite external conditions
What is organization in relationship to the characteristics of Life?
How things work together either in a cell (unicellular) or between each other (multicellular)
Distinguish the difference between (genetic) adaptation and evolution.
Adapt- genetic adaptations; ex: beak size
Evolution- Driven by adaptation
Clarify how cells respond to environmental stimuli.
Must stay within the zone of tolerance; ex: homeostasis
Are viruses alive?
Controversial issue, scientists still are unsure.
Why are cells so small?
- Rate of Diffusion
- Surface area to Volume Ratio
- Amount of DNA
Explain how the rate of diffusion affects cell size.
- The further something is, the longer it takes to defuse
- If the distance is to great within the cell, the cell runs risk of running out of ATP at further distances
- If substances take to long to diffuse, it could lose homeostasis (and therefore die)
Explain how the surface-area-to-volume ratio affects cell size.
- surface determines how much membrane is available to allow substances in and out of the cell (nutrients to enter and wastes to be eliminated)
- volume determines how much cytoplasm there is to use nutrients and to make wastes (essentially metabolism)
- needs surface area to be big enough, smaller cells have larger ratio
- if ratio is to small, cell could lose homeostasis
What is metabolism? Give and describe two examples of metabolism.
Metabolism- All chemical reactions happening in an organism
Catabolic metabolism- extracting chemical energy fro biomolecules (cellular respiration)
Anabolic metabolism- building new biomolecules (dehydration synthesis)
Explain how the amount of DNA affects cell size and how cells can bypass this limitation.
- bigger the cell, the more “parts” it will need and therefore it will need more DNA
- Cells can get around this limitation through genetic duplication and (in the case of some very large protists) have multiple nuclei
Define Endocytosis and Exocytosis.
Endocytosis: Enters the Cell
Exocytosis: Exits the Cell
What are the two different types of cells that exist in nature and what are there differences?
Prokaryotic Cells: Lack a membrane-bound nucleus
Eukaryotic Cells: Possess a nucleus
What domain do Prokaryotes and Eukaryotes belong?
Prokaryotes- Eubacteria and Archaea
Eukaryotes- Eukarya
Compare and Contrast Prokaryotes and Eukaryotes.
- Prokaryotes are structurally less complicated
- Prokaryotes metabolic capabilities as a group exceed those of eukaryotes
- Eukarotes have multiple chromosomes but prokaryotes have a single, coiled chromosomes
- Both have a plasma membrane that separates contents of cell from the environment and regulates the passage of molecules in and out of cytoplasm
How is bacteria present within society and the ecosystem?
- Can cause serious diseases
- Decompose remains of dead organisms
- Contribute to ecological cycles
- Used to manufacture products (industrial chemicals, foodstuffs, drugs (diabetes))
What is the average size of Prokaryotes?
1.1 - 1.5µ wide and 2.0 - 6.0µ long
Name and describe the basic shapes of prokaryotes.
Bacillus: Rod-shaped bacterium (Can occur as pairs or chains)
Coccus: Spherical-shaped bacterium (Can occur as pairs, chains or clusters)
Spirilla: Rigid, long rods twisted into spirals
Spirochetes: Flexible, long rods twisted into spirals
Describe the general organization of bacteria.
Cell Envelope, Cytoplasm, and External Structures
Name the different components of the Cell Envelope.
Plasma Membrane, Cell Wall, Glycocalyx
Describe and state the function of Plasma Membrane.
Phospholipid bilayer with embedded proteins which regulates the entrance and exit of substances into and out of the cytoplasm in order to maintain its normal composition
N.B. In prokaryotes- can form internal pouches called mesosomes which increase the internal surface area for the attachment of enzymes that carry out metabolic activities
Describe and state the function of the Cell Wall.
Maintains the shape of the cell
Contains peptidoglycan, a complex molecule containing a unique amino disaccharide and peptide fragments
Describe and state the function of Clycocalyx
Layer of polysaccharides that lies outside the cell wall in some bacteria
Also called a capsule when the layer is well organized and not easily washed off
“Slime” layer is easily removed
Helps resist a host’s immune system, aids against drying out, and helps bacteria attach to almost any surface
What is cytoplasm?
Semifluid solution composed of water and inorganic and organic molecules (which include enzymes which speed the chemical reactions in metabolism) encased by a plasma membrane
Where is the DNA located in prokaryotes?
In a region of the cytoplasm called the nucleoid
What are plasmids and what are they used for
Extrachromosomal pieces of circular DNA
Used in biotechnology laboratories as a vector to transport DNA into a bacterium
What are ribosomes?
Protein encoded by the prokaryotic DNA that are synthesized on tiny structures in the cytoplasm
Contain RNA and protein in two subunits
Site of protein synthesis
What are cyanobacteria and how did they change Earth’s atmosphere?
Form of bacteria that are capable of photosynthesis in the same manner as plants
Added oxygen which changed atmosphere
What are thylakoids?
Extensive internal membranes found in cyanobacteria’s cytoplasm where chlorophyl and other pigments absorb solar energy for the production of carbohydrates
Why are Cyanobacteria called the blue-green bacteria?
Has a pigment that adds a shade of blue to the cell and has the green color rom chlorophyll
What are the main external structures of a prokaryote and what are they made of?
Flagella, fimbriae, and conjugation pili
Made of protein
Describe the function and structure of flagella.
- Propel motile prokaryotes in water
- Usually 20 nm in diameter and 1-70nm long
- Consists of filament, hook and basal body
- basal body: series of rings anchored in cell wall and membrane
- rotates 360º
- can occur only at two ends of a cell or dispersed randomly over surface
- number and placement can help distinguish prokaryotes
Describe the function and structure of fimbriae.
- small bristle like fibers that sprout from the cell surface
- allow adhesion to surface
Describe the function and structure of conjugation pili.
- rigid, tubular structures
- used to pass DNA from cell to cell
How do Prokaryotes reproduce?
Asexually by binary fission
What is another way they can take up DNA (besides conjugation pili)?
External medium or by way of viruses
What distinguishes eukaryotic cells from prokaryotic cells?
The presence of a nucleus and internal membrane-bound compartments (organelles)
What are organelles?
internal membrane-bound compartments
What feature in eukaryotic cells give them a selective advantage over other cells?
Each organelle carries out specialized functions which allow the cell to be more efficient and successful.
Describe the origin of Eukaryotes. What is this theory called?
Endosymbiotic Theory-
- Original Prokaryotic Cell
- Cell gains a nucleus by the plasma membrane invaginating and surrounding the DNA with a double membrane
- Cell Gains an endomembrane system by proliferation of membrane
- Cell gains mitochondria
- Cell gains chloroplasts
What is the difference between specialized and generalized cells?
Specialized cells do not necessarily contain all the structures of generalized cells
Describe the function and structure of cytoskeleton and what it includes. Is it found in an animal or plant cell?
Maintains cell shape and assets movement of cell parts
Includes-
Microtubules: Protein cylinders that move organelles
Intermediate filaments: Protein fibers that provide stability of shape
Actin filaments: Protein fibers that play a role in cell division and shape
Both Animal and Plant cells
Describe the function and structure of Centrioles. Is it found in an animal or plant cell?
Short cylinders of microtubules
Not found in plant cells but found in animal cells
Describe the function and structure of Centrosomes. Is it found in an animal or plant cell?
microtubule organizing center that contains a pair of centrioles
Both Animal and Plant cells but Plant cells lack centrioles
Describe the function and structure of Vesicles. Is it found in an animal or plant cell?
Small membrane-bound sac that stores and transports substances
Found in animal cells and not commonly found in plant cells
Describe the function and structure of Cytoplasm. Is it found in an animal or plant cell?
Semifluid matrix outside nucleus that contains organelles
Both Animal and Plant cells
Describe the function and structure of the Nucleus. Is it found in an animal or plant cell?
Command center of cell
Includes-
Nuclear envelope: double membrane with nuclear pores that encloses nucleus
Nuclear Pore: permits passage of proteins into nucleus and ribosomal subunits out of nucleus
Chromatin: diffuse threads containing DNA and protein
Nucleolus: region that produces subunits of ribosomes
Both Animal and Plant Cells
Describe the function and structure of Endoplasmic reticulum. Is it found in an animal or plant cell?
Protein and lipid metabolism
Can be-
Rough ER: Studded with ribosomes that synthesize proteins
Smooth ER: Lacks ribosomes, synthesizes lipid molecules
Both Animal and Plant Cells
Describe the function and structure of Peroxisome. Is it found in an animal or plant cell?
Vesicle that is involved in fatty acid metabolism
Both Animal and Plant Cells
Describe the function and structure of Ribosomes. Is it found in an animal or plant cell?
Particles that carry out protein synthesis
Both Animal and Plant Cells
Describe the function and structure of Polyribosome. Is it found in an animal or plant cell?
String of ribosomes simultaneously synthesizing the same protein
Both Animal and Plant Cells
Describe the function and structure of Mitochondrion. Is it found in an animal or plant cell?
Organelle that carries out cellular respiration production ATP molecules
Both Animal and Plant Cells
Describe the function and structure of Golgi apparatus. Is it found in an animal or plant cell?
Processes, packages, and secretes modified proteins
Both Animal and Plant Cells
Describe the function and structure of the Central vacuole. Is it found in an animal or plant cell?
Large fluid-filled sac that stores metabolites and helps maintain turgor pressure
Found in Plant Cells not found in animal cells
Describe the function and structure of Chloroplasts. Is it found in an animal or plant cell?
Carries out photosynthesis producing sugars
Found in Plant Cells not found in animal cells
Describe the function and structure of the Cell Wall. Is it found in an animal or plant cell?
Outer surface that shapes, supports, and protects the cell contains cellulose
Found in Plant Cells not found in animal cells
Describe the system of a cell in general terms.
System of interconnected organelles that work together to metabolize, regular, and conduct life processes
Where does the production of specific molecules take place and what are the made by?
Inside or on the surface of organelles made by enzymes embedded in the organelles’ membranes
Why is the nucleus essential to the life of a eukaryotic cell?
Contains the genetic information that is passed on from cell to cell and from generation to generation
Specifies the information that ribosomes use to carry out protein synthesis
Contains instructions for copying itself
What is nucleoplasm?
The semifluid matrix in the interior of the nucleus
What is chromatin?
Combination of proteins and nucleic acids that is a network of strands that condenses and undergoes coiling into rodlike structures (chromosomes) just before the cell divides
What are chromosomes?
Carriers of genetic information
Combination of proteins and nucleic acids that is a network of strands that condenses and undergoes coiling into rodlike structures
All the cells of an individual contain the same number of chromosomes (Except egg and sperm)
What are genes?
Information organized on chromosomes
Basic unit of heredity
What are the three types of ribonucleic acid (RNA)?
ribosomal RNA (rRNA); messenger RNA(mRNA); transfer RNA (tRNA)
Where is ribosomal RNA produced and what function do they serve?
In the nucleolus (dark region of chromatin where rRNA joins with proteins to form the subunits of ribosomes)
What is the function of messenger RNA?
Mobile molecule that acts as an intermediary for DNA, a sedentary molecule which specifies the sequence of amino acids in a protein
What is the function of transfer RNA?
Participates in the assembly of amino acids into a polypeptide by recognizing both mRNA and amino acids during protein synthesis
What are the necessary components for a functioning ribosome?
A large and small ribosomal subunit, each comprised of a mix of proteins and rRNA
Where do ribosomes occur?
Number varies depending on function
Some occur freely within cytoplasm, either singly or in groups (polyribosomes)
Others are attached to the ER, a membranous system of flattened saccule and tubules
Describe the sequence of events that transfers information from a gene to fa functional protein.
- In the nucleus, the information within a gene is copied into mRNA which is exported through a nuclear pore complex into the cytoplasm
- Ribosomes receive the mRNA which carries a coded message from DNA indicating the correct sequence of amino acids in a particular protein
