Cell Biology 25 (Manual flashcards)
Cell Theory
1) All living things are composed of one or more cells
2) Cells are the smallest unit of all life
3) All cells are created from other cells
What is deductive reasoning
It is the application of cell theory so that educated guesses can be made with relative certainty as all organisms (with some exceptions) will meet these standards
What are the 8 functions a unicellular organism must complete?
- homeostasis
- metabolism
- nutrition
- movement
- excretion
- growth
- stimuli reactions
- reproduction
What defines a eukaryotic cell?
A cell with individual organelles are contained within separate membranes, most importantly they contain their DNA with their membrane-cound nucleus
What are the advantages of a eukaryotic cell?
Ability to act on its own as a fully functioning structure without the need for external influence to function
What are the two types of eukaryotic cells and what is the difference?
- Plant and animal cells
- Plant cells contain extra organelles - cell wall, chloroplasts, and large central vacuole
What is the cytoskeleton?
It is a network of microtubules and microfilaments built within the cytoplasm and destroyed very quickly in order to tranport eseential nutrients and materials around the cell
What are the important details of eukaryotic cells?
- DNA is bound to histones
- Nucear membrane contains pores
- ribosomes are 80S
- The cytoskeleton contains microtubules and microfilaments
- Double-membraned organelles
Which structures are no organelles in a eukaryotic cell
- cell wall
- cytoplasm
- cytoskeleton
Which structures are considered organelles in a eukaryotic cell?
- nuclei
- mitochondria
- golgi
- other major structures bound in membranes
- cell membrane
Decribe the currently accepted cell membrane theory
The model is called the Fluid Mosaic Model, and is considered Amphipathic.
The model is comprised of a phospholipid bilayer, comprised of amplipathic (containing both hydrophobic and philic elements)
What are the essential components of the cell membrane
- fatty acids
- cholesteral
- integrated proteins
- peripheral proteins
- glycoproteins/glycolipids
Describe the fatty acid component of the cell membrane and its function
The fatty acids make up the tail of the phospholipid,
They are non-polar and hydrophobic, meaning that they will avoid water and make up the internal structure of the phospholipid bilayer
- A fatty acid can either be saturated or unsaturated, this will determine the flexibility and melting point of the membrane
- A saturated fatty acid has double bonds of carbon in its chain, making for a higher melting point and less flexible membrane - often found in the flesh of fish at higher temp climates
- an unsaturated fatty acid does nothave double bonds, making the membrane more flexible with a lower melting point, it is often found in the flesh of fish at lower temperatures
Describe the cholesterol component of the membrane
- it acts as a flexibility regulator, meaning it will prevent falling apart at higher temperatures as well as harmful stiffening at lower temperatures
Describe the glycoprotein element of the membrane
- defined as carbohydrate structures connected to some peripheral proteins of the membrane, which act as a way to indentify and connect with other cells
Peripheral and integral proteins
Peripheral - attached to outside or inside of the membrane - important for recognition and adhesion
Integral - go throughout the membrane, play an important part in transporting molecules
What are the finctions of ribosomes and where are they located?
Ribosomes can be either attached to the endoplasmic reticulum or free floating
Free ribosomes synthesize proteins that are used within the cell
Attached ribosomes synthesize proteins that are transported out of the cell and used elsewhere
What is the position and function of the golgi apparatus
The golgi apparatus is made up of flattened discs called cisternae, ands its main function is to package and transport synthesized proteins from the rough ER to out of the cell,
however they also are responsible for the modification and finishing of the proteins sent by the ER
What is the function and process of vesicles
Vesicles are rounded sacs made of one-layer endothelium, and their main function is to contain and transport materials
They are formed with the help of the protein Clathrin. which help in pinching off pieces of membrane and forming them into sacs
What does the acronym CAM stand for?
Cell adhesions molecules
What part of the cell membrane is responsible for the adhesion of cells?
Glycoprotein
What are the three advantages of Eukaryotic cells?
1) Separation of nucleus and ribosomes due to the membrane of the nucleus and the cytoplasm which allows for separation between mRNA and ribosomes, meaning that mistakes and generation can be regulated
2) Compartmentalization of Organelles due to cytoplasm separates incompatible processes
3) double membrane of the nucleus - allows for duplication of DNA material during mitosis/meiosis
What are the 5 different types of cells that can arise from STEM
sperm
ovum
red blood cell
white blood cell
striated muscle cells
How does the size of the sperm cell suit its function?
The small size reduces drag and is caused by the fact the sperm only needs a short-term energy source and DNA material
How does the size of the ovum help its function?
It is the largest of the specialized cells, and requires more food rsserves for reproduction
What are the 4 exceptions to cell theory?
- skeletal muscle - needs more than one nucleus, cannot function on its own
- apesptate fungal hyphae - no separation between cells, no compartmentalization
- red blood cells - no nucleus, cannot duplicate and requires coming from STEM cells
- sieve tube elements - needs partner cell to carry organelles
What is the function of the nucleoid in a prokaryote?
A space of loose DNA material
What is the definiton of a prokaryote?
A cell that does not contain individually membraned organelles
What are the function of plasmids?
Individual autonomous DNA spots in a prokaryote that are transferred during duplication
What is the classification of Ribosomes in a prokaryote?
70S
Where is the slime capsule located?
It is the outer layer of the Prokaryote, it defends from dehydration and phagocytosis
What is the function of the flagella?
A tail with a motor protein on the end of prokaryotics to facilitate movements
What is the function of the Pili?
Hair-like structures that allow adhesion to surfaces or mediate bacterial conjugation
Describe the function of antibodies
Antibodies target the metabolic processes of various bacteria and prevent them from dividing into more and more bacteria, which is the main way they harm their host
They do not work with viruses because they infect the host cells, meaning both would have to be killed
How were antibodies discovered?
Discovered in saprotrophic fungi bacteria, which evolved to secret antibodies to kill the bacteria which was their natural competitor
What is a virus?
a non-cellular agent that infect cells and reproduce inside of them
What are the five characteristics of viruses?
1) Small size, due to lack of cytoplasm and other structures
2) Fixed size as they cannot grow over time
3) nucleic acids as genetic material
4) a capsid encloses their genetic material during reproduction
5) few or no enzymes and reliance on host for metabolism
What are the two aspects of viruses that prove several evolutionary origins?
1) Diversity of genetic material - can come in many different forms, such as RNA and DNA, short and long
2) enveloped vs. non-enveloped viruses - when reproducing viruses burst from the host during a process called lysis, some are enveloped and some are not, non-enveloped viruses infect plants and bacteria rather than mammals
Any structural features similar in viruses, such as their ethod of reproduction, are thought of as convergent evolution due to their multiple types of evolutionary origins
Describe Bacteriophage Lambda
- virus that uses bacterium or archaem as a host
- non-enveloped
- one double stranded DNA molecule
- can follow lytic or lysogenic cycle
Describe COVID-19
- uses animals as host
- enveloped
- one single stranded RNA molecule
- is an exampled of zoonosis
Describe HIV
- retrovirus, meaning it converts RNA to DNA after infecting a host
- enveloped
- two copies of single stranded RNA
- contains enzyme called reverse transcriptase, which allows it to convert RNA into DNA after infecting the host by integrating it into the host's chromosomes
- infect T helper cells of the immune system
Describe the lytic cycle and its steps
- when viruses reproduce and then kill the host when offspring burst out
1) infection and genome injection
2) genome circularizes
3) translation, replication, and assembly
4) lysis and release of progeny - killing the cell
Describe the lysogenic cycle and its steps
- viruses integrate genetic material into that of the host and do not kill it
1) infection and genome injection
2) genome circularizes
3) genome integrates into chromosome of host
4) cell reproduces using the DNA of the virus, creating its offspring
5) cells bud off from the original through fission to produce more viruses
6) genome is exsized from the chromosome once it has completed its purpose
What are the reasons for fast virus infections throughout a population?
- virus generation time is under an hour
- some have no checks in place when duplicating, meaning mutations and natural selection is much more common and new, stronger variants are constantly created
- two examples are influenze and HIV
- makes it difficult for researchers to keep up