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The Animal Cell and Animal Mitosis/Meiosis Procedure on How to Isolate Cheek Cells:
- Rinse your mouth with water.
- With the end of a toothpick, gently scrape the inside of your cheek, util there are cheek cells gathered.
- On a glass slide, place a drop of water using dropper (intended for the scrape to easily transfer from the toothpick towards the glass slide) and add the cheek scrapings.
- Properly and gently stir the scrapings by means of a toothpick until drop becomes cloudy.
- Using again a dropper add a small drop of Iodine into the specimen. Iodine will be use as staining agent in order for us to easily find and locate the cheek cell upon viewing it into the microscope because cheek cell is an example of simple squamous which infers that it is very thin.
- Place a cover glass on the slide to secure the specimen and locked the slide glass with a stage clip to avoid sudden movements that will cause danger, lastly view it under the LPO and HPO. However, if you will not cover it with glass slide on top make sure that you should never allow the lens to touch the slide you are looking at. Dirty lenses can be difficult to clean. Parts of Animal Cell and Their Corresponding Function Animals are a large group of diverse living organisms that make up to three-quarters of all species on earth. With their ability to move, to respond to stimuli, respond to environmental changes and adapt to different modes of feeding defense mechanisms and reproduction, all these mechanisms are enhanced by their constituent elements in the body. However, animals cannot manufacture their own food like plants and hence they depend on plants in one way or another. An animal cell is a eukaryotic cell that lacks a cell wall, and it is enclosed by the plasma membrane. The cell organelles are enclosed by the plasma membrane including the cell nucleus. Unlike the animal cell lacking the cell wall, plant cells have a cell wall. Plasma membrane To enclose and protect the cell content. To also regulate the molecules that pass into and out of the cell, through the plasma membrane. Therefore, it controls homeostasis. The proteins are actively involved in transporting materials across the membrane nucleus Nucleus is enclosed by the nuclear envelope (double-layered membrane). The primary role of the nucleus is to control and regulate cell activities of growth and maintain cell metabolisms. It also carries the genes that have hereditary information of the cell. Chromatin: DNA and DNA-binding proteins. Chromosomal DNA carries the genetic information encoding cellular RNA and protein molecules Nuclear envelope
Separates nuclear contents from cytoplasm. Equipped with complex protein pores which allow movement of molecules between the nucleus and cytoplasm Cytoplasm This is a gel-like material that contains all the cell organelles, enclosed within the cell membrane. These organelles include; Mitochondria, ribosomes, Endoplasmic reticulum, Golgi apparatus, lysosomes intermediate filaments, microfilaments microtubules, vesicles. Mitochondria These are membrane-bound organelles located in the cytoplasm of all eukaryotic cells Their primary function is to generate energy for the cell i.e. they are the power generators, producing energy in form of Adenosine Tri-phosphate (ATP), by converting nutrients and oxygen into energy enabling the cell to perform its function and to also release excess energy from the cell. Power house Mitochondria also store calcium which assists in cell signaling activity, generating cellular and mechanical heat and mediating cellular growth and death Ribosomes Ribosomes that occur as free particles are attached to the endoplasmic reticulum membrane occurring in large numbers accounting for about a quarter of the cell organelles. A single replicated cell has about 10 million ribosomes. The ribosomal subunits are the site for genetic coding into proteins. On the ribosomes, the mRNA helps determine the coding for Transfer RNA (tRNA) which also determines the protein amino acid sequences. This leads to the formation of the rRNA which are involved in the catalyzation of peptidyl transferase creating the peptide bond found between the amino acid sequences that develop the proteins. The formed proteins then detach from the ribosomes, migrating to other cell parts for utilization by the cell. Endoplasmic reticulum Manufacturing, processing and transporting proteins for cell utilization both in and out of the cell. This is because it is directly connected to the nuclear membrane providing a passage between the nucleus and the cytoplasm. Golgi apparatus Their primary function is to transport, modify and pack proteins and lipids into the Golgi vesicles to deliver them to their target sites. Animal cells contain one or more Golgi bodies while plants have a few hundred Lysosomes This is the site for digestion of cell nutrients, excretion, and cell renewal. Lysosomes break down macromolecules components from the outside of the cell into simpler elements that are transported into the cytoplasm via a proton pump to build new cell materials. These macromolecule components include old cells and parts, cell waste products, microorganisms, and cell debris Cytoskeleton
Its main function involves folding in of the plasma membrane. The folding allows diffusing in of molecules through the extracellular fluids. Their primary role is to remove waste materials from the cell by endocytic processes such as exocytosis and phagocytosis Vacuoles their primary function is to store food, water, carbohydrates in the form of sugars and waste materials. Tonoplast is a regulator controlling the inflow and outflow of small across a protein pump. Acts as the guard for what kinds of matter are allowed passage to and from vacuoles Stages in Animal Mitosis/Meiosis, and the Importance of Each Stage G1 phase. Metabolic changes prepare the cell for division. At a certain point - the restriction point the cell is committed to division and moves into the S phase. S phase. DNA synthesis replicates the genetic material. Each chromosome now consists of two sister chromatids. G2 phase. Metabolic changes assemble the cytoplasmic materials necessary for mitosis and cytokinesis. M phase. A nuclear division (mitosis) followed by a cell division (cytokinesis) Mitosis is a form of eukaryotic cell division that produces two daughter cells with the same genetic component as the parent cell. Chromosomes replicated during the S phase are divided in such a way as to ensure that each daughter cell receives a copy of every chromosome. The replicated chromosomes are attached to a 'mitotic apparatus' that aligns them and then separates the sister chromatids to produce an even partitioning of the genetic material. This separation of the genetic material in a mitotic nuclear division (karyokinesis) is followed by a separation of the cell cytoplasm in a cellular division (cytokinesis) to produce two daughter cells. Mitosis, although a continuous process, is conventionally divided into five stages: Prophase, Prometaphase, Metaphase, Anaphase and Telophase. The phases of mitosis Prophase Prophase occupies over half of mitosis. The nuclear membrane breaks down to form a number of small vesicles and the nucleolus disintegrates. A structure known as the centrosome duplicates itself to form two daughter centrosomes that migrate to opposite ends of the cell. The c entrosomes organize the production of microtubules that form the spindle fibres that constitute the mitotic spindle. The chromosomes condense into compact structures. Each replicated chromosome can now be seen to consist of two identical chromatids (or sister chromatids) held together by a structure known as the centromere. Prometaphase
The chromosomes, led by their centromeres, migrate to the equatorial plane in the mid-line of the cell - at right-angles to the axis formed by the centrosomes. This region of the mitotic spindle is known as the metaphase plate. The spindle fibres bind to a structure associated with the centromere of each chromosome called a kinetochore. Individual spindle fibres bind to a kinetochore structure on each side of the centromere. The chromosomes continue to condense. Metaphase The chromosomes align themselves along the metaphase plate of the spindle apparatus. Anaphase The shortest stage of mitosis. The centromeres divide, and the sister chromatids of each chromosome are pulled apart - or 'disjoin' - and move to the opposite ends of the cell, pulled by spindle fibers attached to the kinetochore regions. The separated sister chromatids are now referred to as daughter chromosomes. (It is the alignment and separation in metaphase and anaphase that is important in ensuring that each daughter cell receives a copy of every chromosome.) Telophase The final stage of mitosis, and a reversal of many of the processes observed during prophase. The nuclear membrane reforms around the chromosomes grouped at either pole of the cell, the chromosomes uncoil and become diffuse, and the spindle fibres disappear. Cytokinesis The final cellular division to form two new cells. In plants a cell plate forms along the line of the metaphase plate; in animals there is a constriction of the cytoplasm. The cell then enters interphase - the interval between mitotic divisions Meiosis Meiosis is the form of eukaryotic cell division that produces haploid sex cells or gametes (which contain a single copy of each chromosome) from diploid cells (which contain two copies of each chromosome). The process takes the form of one DNA replication followed by two successive nuclear and cellular divisions (Meiosis I and Meiosis II). As in mitosis, meiosis is preceded by a process of DNA replication that converts each chromosome into two sister chromatids. Meiosis I Meiosis I separate the pairs of homologous chromosomes. In Meiosis I a special cell division reduces the cell from diploid to haploid. Prophase I The homologous chromosomes pair and exchange DNA to form recombinant chromosomes. Prophase I is divided into five phases: Leptotene: chromosomes start to condense. Zygotene: homologous chromosomes become closely associated (synapsis) to form pairs of chromosomes (bivalents) consisting of four chromatids (tetrads). Pachytene: crossing over between pairs of homologous chromosomes to form chiasmata (sing. chiasma).
chromosomes and the traits controlled by them are reshuffled. The genetic mutation occurs due to irregularities in cell division by meiosis. The mutations that are beneficial are carried on by natural selection. Thus, this Crossing over produces a new combination of traits and variations. Mitosis is also important in organisms which reproduce asexually: this is the only way that these cells can reproduce. This is the one key process that sustains populations of asexual organisms. Mitosis allows for some organisms to main alternating life stages (asexual and sexual, such as fungi). Mitosis happens in all eukaryotic cells (plants, animals, and fungi). It is the process of cell renewal and growth in a plant, animal or fungus. It is continuously occurring throughout our bodies; it is even happening while you are reading this. Cells continuously die; this process is termed apoptosis (programmed cell death). For you to stay alive and fully functional, these cells need to be continuously replaced. Mitosis is crucial to this process. Mitosis is the reason we can grow, heal wounds, and replace damaged cells. Do you know the parts of the cheek cell? How does it differ from a plant cell? As in all animal cells, the cells of the human cheek do not possess a cell wall. A cell membrane that is semi-permeable surrounds the cytoplasm. Unlike plant cells, the cytoplasm in an animal cell is denser, granular and occupies a larger space. The vacuole in an animal cell is smaller in size, or absent. The nucleus is present at the center of the cytoplasm. The absence of a cell wall and a prominent vacuole are indicators that help identify animal cells, such as cells seen in the human cheek. Plant cells have a cell wall outside the cell membrane made of cellulose (a plant polysaccharide). Animal cells never have a cell wall. Plant cells have chloroplasts for photosynthesis. Animal cells don’t. Plant cells have a central vacuole for storage of water and nutrients. Animal cells don’t. Plant cells have junctions between each other known as plasmodesmata. Junctions between animal cells are of three types, all of which are very different from the plant junctions. Other than that, plant and animal cells contain largely the same organelles (nucleus, endoplasmic reticulum, Golgi, mitochondria, lysosomes, etc.) Cell Organelles Cell Wall: Protective Coat in Plant Cells The presence of a cell wall is what provides the most significant difference between plant and animal cells, as it is present only in plant cells and covers the cell membrane.The cell wall is rigid and is composed of cellulose fibre, polysaccharides, and proteins. Despite the rigidity of the cell wall, chemical signals and cellular excretions are allowed to pass between cells. Cell Membrane: Protective Coat in Animal Cells The cell membrane is found in both plants and animals, and it is the outer most layer in the animal cell, that separates the contents of the cell from the outside world. It consists of both lipids and proteins and is selectively permeable, which means it permits only some molecules to pass through it. Cytoplasm: Cell’s Inner Space Cytoplasm is a jelly-like material that is eighty percent water and is usually clear in color. It is also called cytosol. Cytoplasm contains all the organelles inside the cell membrane. The cytosol contains dissolved nutrients, helps break down waste products, and moves material around the cell through a process called cytoplasmic streaming. Nucleus: The Control Centre
The nucleus is known as the control center of the cell. It contains the regulatory machinery responsible for all the activities inside the cell. It is the largest organelle in the cell and it contains the DNA of the cell. DNA contains all the information that helps cells live, perform their functions and reproduce. The nucleus has a double layered covering called nuclear membrane. Vacuoles: Cell’s Storage Space A vacuole is a membrane-bound organelle that stores solid and liquid contents. Vacuoles are found in both animal and plant cells, but are much larger in plant cells. Vacuoles are formed by the fusion of multiple membrane vesicles and are effectively just larger forms of these. The organelle has no basic shape or size; its structure varies according to the needs of the cell. Can you see the nucleus? Where is the nucleus located? Yes, we can see the nucleus of the cell. It is located at the center of the cell. Similarities and Differences between Plant and Animal Cells Animal and plant cells have a number of key similarities, but also some noted differences. Here are some of the common similarities and differences between plant and animal cells. Features Animal Cell Plant Cell Cell Shape Round (irregular shape) Rectangular (fixed shape) Cell Wall Absent Present and is formed of cellulose Cell Membrane Present Present and is covered by the cell wall Nucleus Present Present Vacuole One or more small vacuoles A large central vacuole taking up 90% of the cell volume Plastids Present Present Chloroplast Absent Present and make their own food Endoplasmic Reticulum Present Present Ribosomes Present Present Mitochondria Present Present Where can we find mitosis in the cell? Mitosis is a process of nuclear division in eukaryotic cells that occurs when a parent cell divides to produce two identical daughter cells. During cell division, mitosis refers specifically to the separation of the duplicated genetic material carried in the nucleus. Mitosis is conventionally divided into five stages
called a cleavage furrow. Eventually, the contractile ring shrinks to the point that there are two separate cells each bound by its own plasma membrane. Can you find the difference of mitosis and meiosis? Which particular aspect do they differ? Mitosis is when a cell divides to create two identical daughter cells. Mitosis occurs in somatic cells (all the cells that aren’t sex cells), and it’s a process critical for producing new cells and keeping the organism alive and healthy. Most cells in the human body only last a few days to a few weeks (an exception is brain cells, which typically last your whole life), so your body must constantly be making new cells through mitosis. Meiosis also involves cell division; however, it occurs in far fewer cells in your body. The only cells that go through meiosis are gametes, or sex cells (sperm in men and eggs in women). Meiosis is needed for sexual reproduction, and each cycle of meiosis creates four daughter cells with exactly half the number of chromosomes as the parent cell. During fertilization, two daughter cells (one from each organism reproducing) will combine to create an embryo with a full set of chromosomes. Are there mitosis and meiosis in plants? All cells go through a process of formation, growth, division, and eventual death. During mitosis, the parent cell’s nucleus is split to form two sets of chromosomes for each of the new daughter cells. You can learn more about this process by reading our in-depth guide to mitosis. Difference between homologs and chromatids? Homologous chromosomes are 2 physically different chromosomes that have the same genes but are not genetically identical. Sister chromatids are 2 copies of a single chromosome and so are genetically identical (they also are physically attached to one another) Haploid vs Diploid The other main difference between Haploid and Diploid cells is how they reproduce. Haploid cells are formed through meiosis and diploid cells undergo mitosis. Higher organisms such as humans (and most other mammals) are diploid organisms. The major differences are summarized below: Difference Between Haploid and Diploid Haploid Diploid Haploid cells contain only one set of Chromosomes (n). Diploid, as the name indicates, contains 2 sets of chromosomes (2n). Haploid cells are formed by the process of meiosis. Diploid cells undergo mitosis.
In the higher organism, such as humans, haploid cells are only used for sex cells. In the higher organism, such as humans, all other cells beside sex cells are diploid. Examples of haploid cells are gametes (male or female germ cells). Examples of diploid cells include blood cells, skin cells and muscle cells. These cells are known as somatic cells. Haploid Cells Haploid cells contain only one set of chromosomes. Gametes or sex cells are the most common type of haploid cells. They are produced by meiosis and are genetically diverse. When the haploid cells from male and female fuse together during fertilization, it forms a diploid cell. Diploid Cells These cells have two sets of chromosomes. It is formed by the fusion of two haploid cells. Most mammals are diploid, i.e., they have two homologous copies of each chromosome in the cells. They are produced by mitosis. The somatic cells in humans are diploid cells.
