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Processes, Functions and Framework of Cells

  • Cecilia Bromley-Martin

Similarities and variations between prokaryotic and eukaryotic cells


Prokaryotic cells

Eukaryotic cells


Single celled organism

Can be solo celled or multi-celled


Contains cytoplasm, a gel-like substance consisting of cytosol and the cell's organelles

Contains cytoplasm


Contains (smaller) ribosomes to synthesise proteins

Contains (larger) ribosomes to synthesise proteins


Has a tail-like flagellum on beyond cell used to help it move around

Has a flagellum


Can have a cytoskeleton

Always has a cytoskeleton: the internal construction of the cell, composed of health proteins filaments and microtubules in the cytoplasm and maintain the cell form and stability


Genetic material taken in a nucleoid

Has a membrane-bound 'true' nucleus


Organelles are not membrane-bound

Organelles are membrane-bound


Pili support flagellum in helping cell to move around




Mitochondria - the 'powerhouse' of the prokaryotic cell - generate energy from the breakdown of glucose and lipids. They have got outer and interior membranes: the outside membrane contains and ranges them; the inner membrane (cristae) is multi-folded to raise the surface area and thus the quantity of ATP (adenosine triphosphate) that can be produced for cellular reactions.


The small, circular DNA molecules in a prokaryotic cell are called plasmids and - in the lack of chromosomes - these (as well as the nucleoid) carry genetic information.

No plasmids, as eukaryotic skin cells contain chromosomes



For energy, eukaryotic cells in plants likewise have chloroplasts, made up of chlorophyll for photosynthesis.



The endoplasmic reticulum (hard and soft) is where health proteins and steroids are synthesised in the cell, as well being the site of excess fat metabolism. Made up of a series of flattened cavities, the ER also works as a transportation system for other mobile substances. The "smooth" ER produces lipids whilst the "rough" ER synthesises proteins.



The Golgi apparatus is made up of smooth membranes resembling a stack of pancakes. It works together with the endoplasmic reticulum to secrete hormones, enzymes, antibodies and other molecules by modifying and presentation them before a vesicle calls for them away to the cell surface for release.

What are the specialised set ups that allow a sperm to carry out its role?

The spermatozoa's role is to fertilize the female egg to be able to create a zygote. For the sperm to travel to the ovum and penetrate its membrane, it needs energy. This is provided by the large number of mitochondria it includes, which generate energy by means of adenosine triphosphate (ATP). To assist its movements, a sperm also has small, thin cells and an undulipodium (tail) which propels it frontward in a whip-like fashion. To fertilize the egg, the top of the sperm cell also develops an organelle named an acrosome which contains the digestive enzymes necessary to permeate the egg's exterior membrane.

What will be the specialised structures that allow a red blood vessels cell to carry out its role?

The role of the red blood cell is to transport oxygen (in the form of haemoglobin) to other skin cells. Its structure differs from other eukaryotic cells: to be able to maximise the area available for the haemoglobin it holds, the red blood cell will not include a nucleus or mitochondria. It has a slim membrane for air to complete efficiently and is biconcave in form, giving the oxygen a larger surface to diffuse in or out. In addition, it has a adaptable membrane to allow it to pass through smaller capillaries.

The smooth mosaic model is utilized to explain how cell membranes are developed and how they define the perimeter of the cell, keeping substances out up to making some in. What components match this model and what do they certainly? (250 words)

The cell membrane is made up of a phospholipid bilayer. This consists of two tiers of lipids, each which has a phosphate brain (hydrophilic) and two oily acidity tails (hydrophobic). As the phosphate mind are water-loving, these fall into line in a circle on the outside, with the tails facing inwards, to set-up the cell membrane. In this particular tight construct is available cholesterol, which regulates the fluidity of the membrane when it gets warmer or cooler. This is very important because the pieces of the membrane must have the ability to float around constantly - hence the 'smooth' in the liquid mosaic model. A significant amount of proteins can even be within the cell membrane. These are generally trans-membrane proteins (existing across the entire membrane), or peripheral proteins which take a seat on top of the phospholipid bilayer (or together with other protein), but occasionally they may also be found going only half-way through or - even more seldom - relaxing inside the cell membrane. This last is very unconventional because they can not play a significant part in both principle tasks of the protein: as receptors for information from beyond your cell, and assisting to transport molecules in and out of the cell. Your final component in the fluid mosaic model is carbohydrate (sugar). Sticking out of lipids (glycol-lipids) and proteins (glycol-proteins), they play an important role in communication, allowing skin cells to discover other skin cells.

The overall picture created by the phospholipid bilayer, cholesterol, proteins and carbohydrates is one of any mosaic.

Active and Passive carry allows exchange in and out of an cell. What types of transport occur and how are they important?

Passive move in skin cells, which requires no energy, is out there in three forms: simple diffusion, osmosis and facilitated diffusion. Simple diffusion also known as diffusing down a "concentration gradient" - occurs when molecules undertake the cell membrane from a location of greater attentiveness to an area of lesser focus. This form of diffusion is vital as it's the means where oxygen passes into a cell and carbon dioxide passes out. Osmosis, on the other hand, is important when a membrane is permeable only to water, so that larger molecules cannot pass through to an area of lower focus. Water moves through the membrane before concentration on both attributes is identical. In facilitated diffusion, certain substances and ions that are needed by cells - such as sugar and sodium - but which cannot diffuse through the hydrophobic oily acidity tails in the lipid bilayer, are carried by proteins building water-filled pores to do something as transmembrane stations. Facilitated diffusion is unaggressive because no direct energy from ATP is required since it works in the direction of the attention gradient.

Like facilitated diffusion, effective transport allows essential substances such as glucose and amino acids into skin cells. Unlike facilitated diffusion, however, active transport moves molecules against the concentration gradient (low awareness to high amount), therefore requires a cellular energy source (ATP) to get this done. Active transport will take places whenever a cell already has an increased concentration of an molecule inside than outdoor, but still needs them for essential cellular functions.

Mitosis and meiosis have very different biological functions despite being similar. While using the stages of both procedures discuss how both appear while describing why they can be present

Mitosis and meiosis are the two processes where cells divide, the fundamental difference being that mitosis replaces lost skin cells and results two diploid little girl cells with a full match of 46 chromosomes, whilst meiosis is only used for sexual reproduction and ends up with four haploid princess cells with half the most common variety of chromosomes within a real human cell.

Prophase is the first level of mitosis, during which the chromosomes are condensed into dual strands (chromatids) that happen to be joined in the middle by a web link known as a centromere. Necessary protein constructions called kinetochores then hook up to these strands, using spindle fibres (microtubules) which will eventually draw the chromatids aside. A cell nucleus is surrounded by an envelope, and this dissolves during prometaphase, allowing the kinetochores to start moving to either side of the cell, pulling the chromatids with them. During metaphase, the chromatids fall into line down the centre of the cell to get ready for anaphase, when the centromere links break up and the chromatids start moving along the microtubules to each side of the cell. During telophase, the chromatids enhance themselves into chromosomes again, the microtubules disperse and new nucleus envelopes are made in order to set-up nuclei for each and every of the two new skin cells. In the final stage, cytokinesis, the membrane of the initial cell splits creating two new indistinguishable daughter cells. In pets or animals, this happens when the membrane tightens to create a "cleavage furrow" which splits the cell into two; in vegetation, a "cell plate" developed by fused vesicles lined up across the centre of the cell creates a fresh cell wall structure, allowing the two new daughter cells to split apart. Since cells are constantly being broken or dying, mitosis is vital for the growth and repair of skin cells.

Whilst a similar form of cell division, meiosis differs from mitosis in two crucial respects: variant is unveiled, and the first four phases happen twice. The duplication of prophase, metaphase, anaphase and telophase is mentioned using Roman numerals (I or II) and it occurs in order to make four haploid skin cells rather than just both diploid cells created at the end of mitosis. Hereditary variation is vital to evolution, and there are two ways in which it is presented during meiosis I. In crossing over, homologous chromosomes (those made up of one maternal chromosome and one paternal chromosome) form what's known as "recombinant chromosomes" by swapping parts of their genetic material. While crossing over occurs during prophase I, independent assortment happens later in meiosis, during metaphase I. It takes place at the idea when the chromosomes line up randomly across the centre of the cell, in readiness for the split. The random order means that all daughter cell will get a mixture of maternal and paternal chromosomes. The outcome of the second meiotic section is four haploid cells with just half the chromosomes (23) of a standard cell. Depending on whether the new cells are female or male, they then need to fuse with an egg or sperm to make a zygote with 46 chromosomes, that will become an embryo.


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