Chapter 1 biology Flashcards
The human body contains approximately how many cells?
Approximately 37 trillion cells
Bacterial cells outnumber Eukaryotic cells by about how much?
Bacterial cells outnumber Eukaryotic cells by about 10 to 1.
Prior to 1600, how was the organism perceived/viewed? why?
Complete and inseparable into smaller parts.
Due to the inability to see smaller structures through simple instruments like magnifying glass (IE: microscopes were not invented yet).
In 1665, What did Robert Hooke assemble and tested? What did he notice? What he was not able to see
Robert Hooke assembled a compound microscope and tested its properties on a piece of cork.
He noticed a honeycomb-like structure and compared the spaces within the cork to small rooms of a monastery, known as cells.
Because the cork consists of non-living cells, Hooke was not able to see a nuclei, organelles, or cell membrane.
In 1674, what did Anton Van Leeuwenhoek do? What did researchers later noticed?
Anton Van leewenhoek was the first to see a living cell under a microscope.
Cells could be separated and each cell is considered a distinct structure.
They also found that tissues were made of cells, and the function of a tissue is dependent on the function of the cells that make up the tissue.
In 1850, what did Rudolph Virchow reveal?
Diseased cells could arise from the normal cells in a normal tissue.
What are the 4 tenets/principles of the cell theory?
1) The cell is the basic functional unit of life
2) All living things are composed of cells
3) Cells arise ONLY from pre-existing cells
With advances in molecular biology, the 4th tenet/principal was added:
4) Cells carry genetic information in the form of DNA (deoxyribonucleic acid) and it is passed on from the parent cell to the daughter cell.
What is definition of a virus? Explain violates which of the tenets/principles of the cell theory and why?
Small structures that contain its own genetic material, but unable to reproduce on their own.
Accordingly, it violates the 3rd and 4th principles ( cells arise from pre-existing cells and cells carry genetic material in the form of DNA). This is because
- virions can only replicate by invading other organisms (IE: cells)
- and because they use RNA (ribonucleic acid) as their genetic information.
Distinguish between Eukaryotic cells and Prokaryotic cells?
Eukaryotic: 1) Can be unicellular or multicellular. 2) Contain a true nucleus and organelles enclosed in a membrane. (It also have cell membrane, also known as plasma membrane, that separates the cell from the outside environment)
Prokaryotic cells: 1) Always unicellular (single celled). 2) Does not contain a nucleus or organelles enclosed in a membrane. (It also have cell membrane, also known as plasma membrane, that separates the cell from the outside environment)
Differentiate between cytoplasm and cytosol, and mention where are the organelles found?
Both prokaryotic and eukaryotic cells have a cell membrane (plasma membrane). This cell membrane encloses the cytoplasm, where the cytosol is the semifluid substance of the cytoplasm in which the organelles are suspended/floating in it.
The difference is that in Eukaryotic cells the organelles are membrane bound, while in Prokaryotic cells the organelles are not membrane bound.
Describe the plasma membrane (IE: cell membrane) of Eukayoric cells?
Membranes of eukaryotic cells consists of single phospholipid bilayer. This basically means that its external surfaces are hydrophilic (loves water, and thus electrostatically interacting with the aqueous environments inside and outside the cell) and its inner portion is hydrophobic (hates water, and thus provide a highly selected barrier between the interior of the cell and the external environment).
VIP notes:
1) Cytosol allows for diffusion of molecules throughout the cells with the help of cytoskeleton.
2) Within the nucleus, genetic material is encoded in DNA (deoxy-ribo-nucleic acid), which are organized into chromosomes and this genetic material is processed for the replication of the cell.
3) Eukaryotic cells reproduce by mitosis, allowing the formation of two identical daughter cells. Prokaryotic cells reproduce by binary diffusion.
What is the nucleus surrounded by? Describe it?
The nucleus is surrounded by the nuclear membrane or the envelope.
Which is a double phospholipid bilayer membrane (inner membrane and outer membrane) that separates the nuclear environment from the cytoplasm environment.
What are genes, histones, and chromosomes?
Genes: coding regions of the DNA (that will code for proteins)
Histones: Linear DNA wound around organizing proteins called histones (beads on a string).
Chromosomes: The DNA then further wound into linear strands called chromosomes.
what is the nucleolus? It takes how much of the entire nucleus volume and identified by what?
A subsection of the nucleus, where rRNA is synthesized (ribosomal RNA). It is also the ribosomes factory.
Takes up approximately 25% of the entire nucleus volume and can be identified by the darker spot in the nucleus.
What are the nuclear pores?
Small pores in the nuclear membrane that allows a two-way selective exchange of material between the cytoplasm and the nucleus.
What is considered the “power plants of the cell” in reference to their impotant metabolic functions?
Mitochondria
What are the two membranes in the mitochondria and describe their functions?
Outer membrane: serves as a barrier between cytosol of the cell and the inner environment of the mitochondria (basically the inter-membrane space)
Inner membrane: arranged in numerous foldings called **cristae **and contains the molecules and enzymes of the electron transport chain (the process that creates ATP molecules).
What does the numerous foldings (called cristae) of the inner-membrane provide?
Increase the surface area available for electron transport chain enzymes.
What is the Inter-membrane space and the Mitochrondrial matrix?
The space between the outer membrane and inner membrane is called the Inter-membrane space, while the space inside the inner membrane (where the mitochrondial DNA and the molecular complex reside in it) is called the Matrix.
What does it mean for the mitochondria to be a semi-autonomous organelle?
This means that it is an organelle that contain its own double stranded-circular DNA (genes) and replicate independently of the nucleus by binary diffusion.
What is meant by cytoplasmic or extranuclear inheritance?
Transmission of genetic material to daughter cell independent of the nucleus
What does the Serial Endosymbiosis Theory explains? What does the thoery itself state?
It is the theory that explains the formation of some of the membrane-bound organelles (mitochondria, Chloroplasts in plants, and organelles of motility like flagella)
It posits that these organelles formed by the engulfing of one aerobic prokaryotic cell by anerobic prokaryotic cell and, thus, established a symbiotic relationship.
what is the other function of the mitochondria?
Killing the main cell by releasing enzymes from the electron transport chain in order to initiate an Apoptosis process (programmed cell death).
what are lysosomes?
membrane-bound structures that contain hydrolytic enzymes that digest many substrates, including ingested substances by endocytosis and cellular wastes.
The release of the hydrolytic enzymes occur in a process called what? what happens after its release?
The release of the hydrolytic enzymes occur in a process called autolysis.
Like mitochondria, when the lysosome release these enzymes it results initiate an apoptosis process , but here it leads to the degradation of invading or cellular components only (not the whole cell).
What are endosomes? What are the places that endosomes can transport material to and from?
Lysosomes often function in conjunction with endosomes, which are vesticle structures that transport, package, and sort material traveling to and from the cell membrane.
Endosomes can transport materials to the trans-golgi, cell membrane, or to the lysosomal pathway for degradation.
Describe Endoplasmic reticulum (ER)?
Series of double interconnected membranes that are continguous with the nuclear envelope.
The double membrane is folded in numerous invaginations, creating complex structure with a central lumen.
What are the two types of Endoplasmic reticulum? State the function of each one?
Rough ER: have ribosomes, which allow for the translation of proteins destined for secreation into the Rough ER lumen.
Smooth ER: Lack ribosomes, but it is responsible for:
1) Lipid synethesis (like the phospholipids of the cell membrane)
2) Detoxification of certain drugs and poisins.
3) It also transport the proteins from the Rough ER to the Golgi Apparatus.
What is Golgi apparatus?
A structure that consists of stacked membrane-bound sacs
What are the 4 functions of Golgi apparatus?
1) Transport vesicles bring proteins and lipids from the ER (either rought or smooth)
2) In the golgi apparatus cristae, the products are modified by the addition of groups like carbohydates, phosphates, and sulfates.
3) The golgi apparatus then sort the products by introduction of signal sequences, which help to direct the delivary of products to the target cellular location.
4) After modification and sorting, the products are repackaged into secratory vesicles and then leaves the golgi apparatus to either go to a particular location in the cell (can also be the lysosome for degradation if there is excess or if there is malfunctioning in the product) or to be secreted out of the cell by the process of exocytosis.
What are Peroxisomes? 3 functions?
Structure in the cell containing hydrogen peroxide, that:
1) Breakdown long fatty acids via B-oxidation
2) Participate in synthesis of phosolipids and detoxification of harmful substances (like smooth ER).
3) Contain some of the enzymes involved in the pentose phosphate pathway.
What are the 4 functions of cytoskeleton?
1) Provides structure to the cell and helps it to maintain its shape
2) Provides pathway for the transport of materials and organelles around the cell.
3) Assists in cell division
4) Aids in the movement of the cell.
