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Unit 5 Cell Biology Illustrated Report

This is an illustrated report required as part of the initial learning...

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Academic year: 2021/2022

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Unit 5: Cell Biology

Faye Taylor 02/08/

Introduction

The purpose of this illustrated report is to exhibit the understanding of cell biology.

In the first section, it will look at living cells and their various characteristics. Also included will be comparisons of prokaryotic and eukaryotic cells and how they are impacted by viruses. It will also discuss the organelles and sub-cellular structure of eukaryotic cells.

Within the second section, it will demonstrate the understanding of cellular metabolism. It will do this by explaining the role that the cell membrane plays in controlling the movement of nutrients and waste products. This section will also include an explanation as to how animal cells gain energy from nutrients to enable, movement, growth, and cell division. There will be a discussion on nucleic acids and the role they play in the nucleus and cytoplasm, along with a further discussion on the synthesis of proteins.

The third section will go on to explain how cells grow and divide based on how embryonic stem cells generate specialised tissues. The report will then follow on to demonstrate the process and initiation of cell division and how each daughter cell receives the same genetic information. The final part of this section will include the comparison of cancer cells with normal cells.

Embryonic stem cells .................................................................................... ............................. 21

Interphase and factors that initiate cell division .................................................................... 22

Daughter cells and how genetic information is received ......................... ............................. 23

Comparison and contrast of cancer cells with normal cells ...................... ........................... 25

Conclusion ........................................................................................................................... ........ 26

Recommendations ............. ........................................................................................................ 27

References ........................................................................................................................... ........ 28

Bibliography .................................................................................................................... ............ 29

Section 1: Cell Structure

Living cell characteristics

A living cell, as opposed to a non-living cell, will demonstrate and perform certain characteristics which enable it to survive. It requires energy to allow it to carry out it’s many functions, including cell division, adapting to surroundings and being self-sufficient.

There are seven characteristics of life that apply to living cells and organisms.

 M ovement – they can move and change position  R eproduction – able to produce offspring (the method varies from binary fission, mitosis or meiosis, depending on the cell type)  S ensitivity – ability to detect and respond to stimuli  G rowth – able to increase in size  R espiration – they can create chemical reactions to produce energy  E xcretion – they can remove toxic materials and excess substances  N utrition – able to absorb nutrients and utilise them

A useful acronym to help remember the characteristics is: MRS GREN

[CITATION Var21 \l 2057 ]

Prokaryotic and Eukaryotic cell structure and comparison

There are two types of living cells: prokaryotic and eukaryotic. They have several differences, but the main ones are that prokaryotic cells are single-celled organisms without a true nucleus, where as eukaryotic cells can be either single-celled or multicellular with a nucleus.

 Plasma membrane – located beneath the cell wall, it controls the movement of substances in and out of the cell  Cytoplasm – a gel-like substance that contains various organic molecules and cell components  Flagellum – tail-like structure which aids movement  Pilus – allows the cell to stick to various surfaces  Nucleoid – contains genetic information (chromosomes and DNA)  Ribosomes – aids protein creation

Eukaryotic cell structure

Figure 3 - microbiologynote/prokaryotic-cell-and-eukaryotic-cell/ Accessed 01/08/

The eukaryotic cell has some similarities but is more complex and contains several organelles and a nucleus. The diagram above shows how the structure differs to that of the prokaryotic cell.

 Cell wall – provides rigidity  Plasma membrane – located beneath the cell wall, it controls the movement of substances in and out of the cell  Cytoplasm – a gel-like substance that contains various organic molecules and cell components  Cytoskeleton – protein filaments that provides shape and support to the cell

 Cell organelles: Nucleus – has a membrane and nucleolus and controls various actions within the cell Mitochondrion – produces energy Ribosomes – produces protein Golgi body – processes proteins Lysosome – contains digestive enzymes to help to create fuel for the cell and break down waste matter Endoplasmic Reticulum – helps move items around the cell Peroxisome – are similar to lysosomes and contain digestive enzymes to breakdown metabolic hydrogen peroxides.

Prokaryotic and Eukaryotic cell comparison

Characteristics Prokaryotic Eukaryotic Single celled or multicellular

Single celled Single and/or multicellular Size 0 to 5 micrometres 10 to 100 micrometres Reproduction method Binary fission Mitosis and meiosis Cell wall Yes Not all eukaryotic cells Single membrane Yes No Plasma membrane Yes Yes Cytoplasm Yes Yes Cytoskeleton No Yes Flagellum Yes Not all eukaryotic cells Pilus / Pili Yes No Nucleus No Yes Organelles No Yes Ribosomes Yes Yes Chromosomes / DNA Yes Yes

[CITATION AnI21 \l 2057 ]

Eukaryotic cells - sub-cellular structure and organelles

Let’s take a more in-depth look in to the structure of a eukaryotic cell and the different roles the organelles play.

A cells survival depends upon its ability to carry out specific functions and each part of the cell serves a specific purpose.

Figure 5 - microbiologynote/prokaryotic-cell-and-eukaryotic-cell/ Accessed 01/08/

Cytoplasm

This is the substance within the cell that contains various chemicals and nutrients, including enzymes and amino acids, which allow the cell to function. The organelles are suspended within this solution.

Nucleus

This is the control centre of the cell, the largest organelle and where DNA is stored. It produces RNA (ribonucleic acid), protein and ribosomes.

Nucleolus

The nucleolus is a dark region of chromatin within the nucleus and assists with the production of ribosomes.

Mitochondrion

This is the organelle involved in aerobic respiration. It converts energy from food in to materials that the cell can use.

Ribosomes

These are the smallest and most abundant of the organelles within the cell. They are responsible for protein synthesis. They can be found either within the cytoplasm or on the endoplasmic reticulum (rough).

Smooth Endoplasmic Reticulum

This is a series of membrane channels involved in the transport and synthesis of lipid materials (fats).

Rough Endoplasmic Reticulum

The rough endoplasmic reticulum is the same as the smooth endoplasmic reticulum but the presence of ribosomes makes it textured. It processes the proteins created by the ribosomes as well as being able to add carbohydrates to them. It then removes them from the cell via the Golgi body.

Golgi body

The Golgi body takes the proteins created by the rough endoplasmic reticulum and adapts them so they can be used within the cell. As the proteins move through the Golgi body, they are released in small sacs which either move to other parts of the cell or attach to the cell membrane where the contents is then secreted.

Vacuole

The vacuole is the cells storage organelle. It holds nutrients, water and salts.

Lysosome

There are several lysosomes and they are the digestive and waste processing system within the cell. They digest unwanted materials.

Cytoskeleton

The cytoskeleton are protein filaments that, as the name would suggest, provide support within the cell. They are also involved in the movement of chromosomes whilst cell division occurs.

There are different types of proteins. An intrinsic protein reaches from the outer layer of the membrane to the inner layer, and allows selected nutrients in and waste products out.

An extrinsic protein reaches halfway through the cell membrane. These, combined with carbohydrate chains, are glycoproteins. These act as receptors for cell signalling, which allows the cell to develop, adapt or grow accordingly.

Cholesterol

This adds stability to the membrane and maintains the structure of the bilayer.

The membrane is referred to as ‘fluid’ because the components within it are able to move. The way in which the components deal with nutrients and waste depends on what the substance is. There are various methods.

Classification Method Substances

Lipid diffusion

Simple diffusion which occurs through the lipid bilayer of the membrane

Carbon dioxide, oxygen, water and steroids

Osmosis

Movement of water molecules from a high concentration solution, to that of a low concentration, through the membrane

Water

Facilitated diffusion

Using the transport/carrier proteins which are substance specific

Ions and glucose

Active Transport

Specific transport/carrier protein – pump molecule. This method requires energy

Sodium and potassium

Vesicles

Used to transport larger molecules – both digestion and secretion

Starch, hormones and digestive enzymes

How animal cells use nutrients to provide the energy for growth, movement, and cell division

In order to grow, move and divide, cells need energy. They create that energy from nutrients via a process called cellular respiration.

Cellular respiration is a three-stage process that takes glucose and oxygen and turns it in to Adenosine 5'-triphosphate, also known as ATP. ATP is the molecule for transferring and storing energy within the cells. [ CITATION Bio21 \l 2057 ]

Figure 7 - biologyonline/dictionary/cellular-respiration accessed 03/08/

Stage 1 – Glycolysis

Glycolysis is a series of chemical reactions in the cytoplasm of the cell that breaks down glucose in to two molecules of pyruvic acid. The process, whilst creating energy is using energy at the same time. It’s not 100% efficient. The pyruvic acid makes its way to the mitochondrion

The electron transport chain can make 36 molecules of ATP, compared to 2 during glycolysis and only 1 during the Krebs cycle. [ CITATION BDE19 \l 2057 ]

Figure 10 - medium/countdown-education/3-simple-stages-in-cellular-respiration-and-how-they- work-4de3abc5f819 accessed 03/08/

What are nucleic acids and what role do they play?

Nucleic acids are found within all cells and are made up of chains of nucleotides. They are information carriers, with the primary forms being deoxyribonucleic acid (DNA) and ribonucleic acid (RNA).

They comprise of 3 major components:

 A phosphate group - phosphoric acid  A sugar group - pentose sugar (5-carbon sugar), of which there are two types: deoxyribose (found in DNA) and ribose (found in RNA).  Nitrogen bases. There are two groups: Pyrimidines (cytosine, thymine and uracil) and purines (adenine and guanine). The organic bases are bound together in specific pairings – Adenine with Thymine and Cytosine with Guanine.

The sugar and phosphate group connects the nucleotides together to form the DNA/RNA strand.

Figure 11 - byjus/biology/dna-structure/ Accessed 03/08/

DNA Function – It is required for the production of proteins, the reproduction of cells and carries hereditary information. It remains within the nucleus of the cell.

Here’s a more detailed look at the synthesis of proteins and the stages involved.

Figure 13 - technologynetworks/applied-sciences/articles/essential-amino-acids-chart- abbreviations-and-structure-324357 accessed 04/08/

Transcription

The initial stage begins in the nucleus where part of the DNA molecule breaks its bonds and unwinds. It then pairs with the nucleotides of RNA to form mRNA. The newly created mRNA leaves the nucleus via a pore, enters the cytoplasm and attaches itself to a ribosome.

Activation

Within the cytoplasm, small molecules of tRNA bond with amino acids which then make their way to the ribosome.

Translation

The mRNA is read by the ribosome, three bases (codons) at a time, and the tRNA molecule with the corresponding anti-codon comes in with the

amino acid attached to it. The ribosome then reads the next three codons, the corresponding tRNA comes in and its amino acid creates a peptide bond to the existing amino acid. The initial tRNA is then released, the next three codons are read, the matching tRNA comes in, its associated amino acid attaches to the chain, and so on until the mRNA has been completely read up until the ‘stop codon’. The amino acid chain then folds up and is now able to be used. [ CITATION Lod00 \l 2057 ]

Section 3: Cell Division and Growth

Embryonic stem cells

Stem cells are cells that are undifferentiated, which means they are non- specific and able to become any type of cell. There are several types of stem cells including adult, foetal and embryonic.

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Unit 5 Cell Biology Illustrated Report

Module: Access To Higher Education Diploma (Midwifery)

77 Documents

Students shared 77 documents in this course

University: Learndirect

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