Unit 5 - final PDF

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UNIT 5 – CELL BIOLOGY Toni Kinsella

Contents Page Introduction

1. Characteristics of Living Cells 2. Prokaryote and Eukaryote Cells and Viruses 3. Eukaryote Sub-cellar Structure and Organelles 4. Cell Membrane 5. Synthesis of Proteins 6. Nucleic Acids 7. Stem Cells 8. Cell Division 9. Animal Cells 10. Cancer Cells 11. Conclusion 12. Reference List and Bibliography

Introduction This report is to demonstrate the understanding of cells biology. This report will look into the characteristics of cells, how cells survive, structure of a cell, the difference between prokaryotic and eukaryotic cells and what impact viruses have on them. Throughout this report will be my in-depth research into the sub structure of the eukaryotic and prokaryotic cells and their organelles, as well showing how they react within viruses, also animal and cancer cells and how they work. Then providing an analysis into the respiration, synthesis and movement of what nucleic acid plays in the nucleus and the cytoplasm. Finally, this report will look into the generation of specialised tissues from embryonic cells, importance of interphase and factors that initiate cell division, such as mitosis and how daughter cells are formed from this. Finally, this report will compare cancer cells.

Characteristics of Living Cells A cell is a characteristic of life. The cell was first discovered in the 17th century when a scientist called Robert Hooke (1665) described the first found cells in cork and that led to the scientist Anton Can Leuwenhoek (1675) to discover the protozoa cell, which then lead to bacteria in cells being found nine years later. (https://bitesizebio.com/166/history-of-cellbiology/) Here are the main seven characteristics that all cells must follow in order to survive:

1. Movement - crucial for the cell to be able to move and change position, this gives the organism the opportunity to catch food and avoid predators. 2. Respiration - coverts energy from carbohydrates and fats into energy which is used by the cells. In multicellular organisms the process of respiration breaks down sugars with the use of oxygen. 3. Sensitivity - this allows organisms to detect or sense stimuli, responding to changes in the environment accordingly to protect themselves. 4. Growth – Growth happens in the respiration process, excess energy it provides allows the organism to increase in size, aiding the production of new cells and tissues. 5. Reproduction - comes in two forms, asexually - the creation of a new organism from an existing one through cell division or sexually which requires two organisms to reproduce. 6. Excretion - is vital for the organism to remain healthy; cell and tissue functions produce waste (dead cells, urine), these waste products must be excreted as if remains in the organism can become toxic.

7. Nutrition - is key for survival; food is required for energy and provides essential nutrients to aid growth and the ability to reproduce. (CK-12 Foundation, 2020) All cells must be self-sufficient along with holding an ability to reproduce this can be in forms of binary fusion, mitosis or meiosis. The life span of every cell is variable. All cells require an energy source, many are from metabolic pathways and stored in the form of adenosine triphosphate. Cells will require this energy to respire which may be anaerobic or aerobic (depending upon the use of oxygen). As well as making use of enzymes and catalysts for a faster chemical reaction. Normally, cells grow to a certain size and then stop. Cells cease growing because of intrinsic and extrinsic factors. Growth factors are proteins in the cell’s environment that attach to the plasma membrane, directing cells to continue growing. Growth factors cause cells to grow without initiating cell division.

Prokaryotic and Eukaryotic Cells

Prokaryotic Cells Prokaryotic cells member bound organelles (nucleus and mi t ochondr i a) . Bacteria are amongst the simplest of organisms - they are made of single cells. Their cell structure is simpler than the cells of eukaryotes and cells are smaller, most are 0.2 μm - 2.0 μm. Prokaryotic are one of the simplest cells of life, they reproduce very quickly and achieve cell division using binary fission meaning the cell will spilt into two identical cells. Prokaryotic cells are anaerobic (respire without the use of oxygen), this happens within the cytoplasm, their DNA is a single circular chromosome called plasmids and is contained in the central are by the nucleoid. (Bitesize 2020)

Eukaryotic Cells Eukaryotic cells are cells that contain a nucleus and organelles, and are enclosed by a plasma membrane. Organisms that have eukaryotic cells include protozoa, fungi, plants and animals. Eukaryotic cells

are larger and more complex than prokaryotic cells, which are found in Archaea and Bacteria, the other two domains of life.

Comparison Prokaryotic and Eukaryotic cells are the division of two living organisms. All cells fall into one of these categories, whilst they do share a lot of similarities, they have a unique structure and function differently. For example both sets of cells are made up of DNA as a genetic material but a defining feature is that eukaryotic cells have a nucleus classing this as complex cell were as a prokaryotic cell has no nucleus which classes this as a simple cell. Eukaryotic cells are found within animals and plants were as prokaryotic cells are found within bacteria. I have created a table below show the key differences between the two cells: https://www.visiblebody.com/learn/biology/cells/ prokaryotes-vs-eukaryotes Prokaryotic

Eukaryotic

No Nucleus

Nucleus

No Organelles

Cytoskeleton

Simple cell structure

Complex cell structure

No Membrane organelles

Membrane organelles

Nucleoid

Chromosomes

Primitive

Contains a cell wall

Unicellular

Multicellular

DNA is free within nucleus

DNA within nucleus

Smaller cells

10x larger prokaryotic cells

Can respire without the use of oxygen

Depends on oxygen on whether it can respire

0.1-5 μm

10-100 μm

Lysosomes and Peroxisomes absent

Lysosomes and Peroxisomes present

Cytoskeleton absent

Cytoskeleton present

As shown above the differences between each cell i.e. shape, size and how both work.

Viruses Viruses are not living things so they cannot live independently and cannot metabolise. Once the viruses decides to enter the cell they will need to enter through the molecules of protein, the envelope of fat and capsid before reaching the DNA or RNA genes within the cell. A virus would insert its genetic material into the host cell and take over its functions. That would force the cell to create more viral protein and genetic material over its normal products. (FS Cohen 2016)

(https://open.oregonstate.education/generalmicrobiol gy

o /

chapter/introduction-to-viruses/)

Eukaryote Sub-cellar Structure and Organelles The Eukaryotic cells contain a nucleus and organelles enclosed by a plasma membrane. They are found in all the eukaryotic organisms. The eukaryotic organisms include four kingdoms: kingdom Protista, kingdom Fungi, kingdom Plantae and kingdom Animalia. Prokaryotes do not have membrane bound organelles whereas eukaryotes have based on the genetic materials enclosed by the nuclear envelope. ‘It is believed that eukaryotes have been evolved from the prokaryotes. They have been characterised by their membrane nucleuses’. Here is a list of the Eukaryotic cells that contain organelles:

1. 2. 3. 4.

Mitochondria (Cellular Energy) Golgi Apparatus (Sectorial Device) Endoplasmic Reticulum (a canal like system of membrane within the cell) Lysosomes (digestive apparatus within many cell types)

I have created a Organelle Nucleus

and organelles: Function  Largest membrane (organelle)  Double nuclear membrane and nuclear pore The nucleus is the largest membrane-bound organelle, it has a double nuclear membrane and a nuclear pore. Described as the hub of a cell.

Cytoplasm

Mitochondria

Contains salts, sugars, enzymes and amino acids  Located within the cell membrane Often referred to as a cytosol. The cytoplasm contains enzymes, sugars, salts, amino acids, and nucleotides. The enzymes are used for metabolic reactions, Located within the cell membrane.  Long shape  Double membrane 

Most important function is to produce energy, stores it as ATP molecules. It also referred as the ‘powerhouse cell’. Ribosomes

Smallest membrane (organelle)  Most common found  Found in the cytoplasm  Attach themselves to the rough endoplasmic reticulum Ribosomes are the smallest organelle, they are the most numerous found. They are the site where proteins are made and synthesized. They are found within the cytoplasm, also attach themselves to the surface of the rough endoplasmic reticulum (RER) 

Cytoskeleton

 

Made from microfilaments and microtubules Contains shape and motility (due to above bullet point)

The cytoskeleton is made up of microfilaments and microtubules, the main purpose of this is to maintain the cells' shape, support, and motility. Nucleolus

  

Made from chromatin Part of the creation of ribosomes Located within nucleus

This is made up of chromatin and is involved in the manufacturing of ribosomes. Located within the nucleus. Lysosomes

Golgi Apparatus



Contains digestive enzymes to break down old cells, food molecules, old organelles and pathogens

Breaks down and removes wastes, digests dead, damaged cells which pose threats bacteria.  Flattened membranes  Also referred to as ‘cisternae’  Proteins move through Golgi body  Receives proteins from RER The Golgi body is a series of flattened membranes referred to as cisternae. Its primary function is to receive proteins from the RER and repackage these for use or secretion. Proteins are moved throughout the Golgi body being modified if necessary. As transferred the membrane pinches inward to form vesicles.

Cell Membrane The cell membrane (or plasma membrane), provides protection for a cell. It also provides a fixed environment inside the cell, and that membrane has several different functions. They are the building blocks of all organisms. Some living organisms are made up of only one cell and are called unicellular, while the rest are made up of many cells called multicellular organisms. In both unicellular and multicellular organisms, the cells are kept separated from each other and surroundings by a barrier called plasma membrane or cell membrane. https://www.britannica.com/science/cell-membrane

The membrane is made up of two different parts covered with phospholipid (polar) as the outer layers and fatty acid phospholipid (nonpolar) as the inner layers, both connected to the integral (intrinsic) proteins in the centre of the membrane. On the top layer of the membrane there are sugar side chains placed throughout the layer as well as cholesterol running through from the outer layer down to the inner face.

Gained Nutrients and Waste Products The cell membrane excerpts waste and gains nutrients by from transferring substances, this can be in all different ways depending upon the substances nature. A few ways a membrane does this is explained below:

Lipid Lipid diffusion is used for steroid transportation. The Lipid bilayer allows small substances such as oxygen, carbon dioxide, and hydrophobic molecules to pass through the cell membrane and then pass down their concentration gradient into simple diffusion.

Facilitated Facilitated diffusion is also used through concentration gradient with non-recurring energy and then classed as a passive transport. Facilitated diffusion is also known for the diffusion of solutes through transporting proteins in the plasma membrane classed as channels and carriers.

Passive Transport Passive transport occurs when molecules diffuse across the cell membrane by passing through certain transportation proteins. The transportation happens when a high concentration molecules needs to go to a lower concentration. There is no use of energy in this as it goes with the concentration gradient. BBC Bitesize 2020

Active Transport Active transport occurs when molecules at a low concentration are moved by different transport proteins across the cell membrane into a higher concentration. This movement require energy as it goes against the concentration gradient. ‘Energy is provided by the breakdown of ATP inside the cell. (BBC Bitesize 2020)’.

Vesicular transport Vesicular transport is the predominant exchange of proteins and lipids between membranebound organelles in eukaryotic cells. There are three types of transport vesicles, as shown below: 1. Clathrin Coated – Clathrin coated vesicles are formed from both the plasma membrane and the transGolgi network. 2. COPI Coated COPI coated vesicles and COPII-coated emerge from the endoplasmic reticulum (ER) in order to export new proteins towards the Golgi. 3. COPI - COPI vesicles appear in both biosynthetic (anterograde) and retrograde transport, within the Golgi complex. COPI mainly recycles proteins from the Golgi to the endoplasmic reticulum (ER). Golgi-derived COPI-coated vesicles are involved in several vesicular transport steps, including bidirectional transport within the Golgi and recycling to the ER. (Company of Biologists 2020)

Respiration ATP is made within the respiration process; ATP can be hydrolyzed into ADP/PI with the use of active transport. ATP is vital to cell’s survival as it will release energy when require for chemical reactions. It is dependent on the trophic levels of food to provide energy sources to be chemically changed into ATO. The mode widely used substrate for respiration is glucose, but may use proteins and liquids. Energy nutrients can be stored for future use. The three stages to cellular respiration are 1. Glycolysis – This occurs within the cytoplasm and can happen with or without oxygen. 2. Krebs cycle – it is a complex series of biochemical pathways which is better known as above, this occurs within the mitochondria and is a series of chemical reactions to release stored energy (BD editors 2019) 3. Electron transport – this is the final stage of respiration, this occurs within the inner membrane of the mitochondria

Transcription Transcription occurs within the nucleus. Hydrogen bonds break between the bases of the DNA molecule causing unwinds, allowing the free RNA nucleotides to pair with exposed single strand of DNA, the sugar phosphate also bonds commonly cytosine with guanine and adenine bonds with thymine within DNA but uracil within RNA. Forming a single strained molecule referred to as the messenger RNA.

Activation Activation occurs within the cytoplasm, within are free amino acids as well as transfer RNA. The amino acids bind with the TRNA the process of this is down to the specific enzyme and requires a source of energy. TRNA has 3 unpaired bases that are known as anti-condon. Translation Translation occurs within the ribosomes. MRNA attaches itself to the larger subunit the first three are AUG (adenine, uracil and guanine) structured. TRNA constructs the amino acids of methionine which is why within the polypeptide chain this is always first. Secondly a TRNA molecule will then bind the remaining three which will be on a complementary basis of anticonden, this introduces the second amino acid depending upon which TRNA were involved in these bonds.

Animal Cells Animal cells are eukaryotic cells or cells with a membrane-bound nucleus. Unlike prokaryotic cells, DNA in animal cells is housed within the nucleus. With having a nucleus, animal cells also contain other membrane-bound organelles, or tiny cellular structures, that carry out specific functions necessary for normal cellular operation. Inside the cell, each organelle performs the specific task. All organelles are not present in all the animal cells. Cell growth comes from the metabolism process which is a two-part process, catabolism and anabolism. Catabolism firstly breaks down complex molecules into smaller ones, releasing energy which is stored as Adenosine Triphosphate know as ATP. The catabolism then increases the ATP concentration by breaking down nutrients and food, synthesised cell

molecules for this process are proteins, lipids, carbohydrates, nucleic acids such as DNA and RNA. The anabolism process takes smaller molecules and builds them up into more complex ones, using the energy fuelled through ATP. The smaller molecules are joined to make bigger and different molecules referred to as macromolecules. Anabolism use these macromolecules to build cells and help new cells which are essential for growth, building organs and tissues. (BBC Bitesize, 2020)

Here are the few functions of Animal Cell: 1. 2. 3. 4. 5.

These cells control the processes in the body efficiently. Cells control synthesis and storage of energy. Cells also perform and control the Replication, Translation, and transcription of DNA. Cells are extremely dedicated to carrying out precise responsibilities. Red blood cells encompassed of Hemoglobin. Hemoglobin is the cells which did not contain any nuclei and its main function is to transfer oxygen throughout the whole body. 6. Inside the human body, ciliary cells are present in the Digestive Tract which increase the surface area and help in the process digestion. 7. Numerous cells syndicate and form Tissues. Which perform a specialised function in the human body. 8. Analogous tissues assembled and form the organs of the body, like lungs, brain and heart.

Nucleus Acids Nucleic acids are essential biomolecules that are present in every form of life that we live in. They are present in all organisms from animals and bacteria to viruses and humans. Nucleic acids range in size from small biomolecules to large biopolymers. They are made up of repetitive subunits called nucleotides. The word nucleic acid is used for DNA and RNA. (https://alevelbiology.co.uk/notes/nucleic-acids/) Both nucleic differ in size, shape, location and function within the cell, as shown below.

RNA RNA is also present in almost all living cells. RNA is the second most important nucleic acid present in the living things. It is a polymer of ribonucleotides having ribose as pentose sugar.

Transfer RNA (tRNA) Transfer RNA transfers amino acids to the ribosomes so that they can be assembled into proteins. The RNA reads the code on the messenger (mRNA) RNA and carries the specific amino acids to the ribosomes so it can be transferred to the correct proteins.

Messenger RNA (mRNA) The messenger RNA is responsible for the messages between the DNA and cytoplasm. It carries information for the present proteins within the nucleus of DNA to the ribosomes in the cell cytoplasm.

Ribosomal RNA (rRNA) Ribosomal RNA is the most abundant RNA present in cells. It is an essential component of ribosomes present in bacterial and eukaryotic cells. The ribosomal RNA arranges itself into two subunits, a larger ribosomal subunit and a smaller ribosomal subunit. The structure of these two subunits differs in prokaryotes and eukaryotes.

DNA DNA is present in everything living thing. Eukaryotic cells is entirely made by DNA as they bases and adenine, guanine and cytosine and thymine. Every cell consists of the same quantity of DNA. The most important function of the DNA is to store genetic information.

DNA Replication DNA replication is the process by which DNA is completely copied and created. DNA strands are...