Bio final topics answers

XX vs XY

XX are female chromosomes while XY are male chromosomes

Ion channels?

A single protein or protein complex that traverses the lipid bilayer of cell membrane and form a channel to facilitate the movement of ions through the membrane according to their electrochemical gradient Ion channels may be open or gated. The potassium leak channel is an example of open ion channel. Gated ion channels may be voltage-gated, ligand-gated, or mechanically-gated channels. Ion channels are the common targets of pharmaceutical drugs, directly or indirectly, since they are capable of regulating the flow of ions to and from the cell. Many ions play in important physiological role in the normal metabolism of cells.

What trait in humans is controlled by multiple alleles?

A trait controlled by one gene but multiple alleles is blood type. There are 4 phenotypes: A, B, AB, O. Types A and B are codominant, and O is recessive to A and B. None are dominant.

Where is ATP produced?

ATP is produced via cellular respiration in the mitochondria and photosynthesis in chloroplasts

How many chromosomes do humans have? How many pairs?

Humans have 46 chromosomes and 23 pairs

What is ATP?

a nucleotide that contains a large amount of chemical energy stored in its high-energy phosphate bonds. It releases energy when it is broken down (hydrolyzed) into ADP (or Adenosine Diphosphate). The energy is used for many metabolic processes. Hence, ATP is considered as the universal energy currency for metabolism

Punnett squares

A diagram that is used to predict an outcome of a particular cross or breeding experiment. It is named after Reginald C. Punnett, who devised the approach. The diagram is used by biologists to determine the probability of an offspring having a particular genotype. The Punnett square is a tabular summary of possible combinations of maternal alleles with paternal alleles. These tables can be used to examine the genotypic outcome probabilities of the offspring of a single trait (allele), or when crossing multiple traits from the parents. The Punnett Square is a visual representation of Mendelian inheritance. It is important to understand the terms "heterozygous", "homozygous", "double heterozygote" (or homozygote), "dominant allele" and "recessive allele" when using the Punnett square method.

Genotype vs phenotype.

An organism's genotype is the set of genes that it carries. An organism's phenotype is all of its observable characteristics — which are influenced both by its genotype and by the environment. So in defining evolution, we are really concerned with changes in the genotypes that make up a population from generation to generation. However, since an organism's genotype generally affects its phenotype, the phenotypes that make up the population are also likely to change. For example, differences in the genotypes can produce different phenotypes. In these house cats, the genes for ear form are different, causing one of these cats to have normal ears and the other to have curled ears.

What are chromatids?

When a chromosome is replicated before mitosis or meiosis, the two identical copies stay bound to each other at first and are called sister chromatids. A chromatid, then, is one copy of a duplicated chromosome.

What does a nucleotide consist of?

sugar, phosphate, and a base

What is equilibrium?

(1) The condition in which all acting influences are balanced or canceled by equal opposing forces, resulting in a stable system (2) The state of balance or static; the absence of net tendency to change Homeostatic equilibrium is the state of equilibrium in homeostasis in organisms. It entails physiological regulations of the internal environment.

What organelles are found in plant cells?

1. PLASMA MEMBRANE/ CELL MEMBRANE Structure- a bilipid membraneous layer composed of proteins and carbohydrates. It is fluid like. Function - the cell membrane separates the cell from its external environment, and is selectively permeable (controls what gets in and out). It protects the cell and provides stability. Proteins are found embedded within the plasma membrane, with some extending all the way through in order to transport materials. Carbohydrates are attached to proteins and lipids on the outer lipid layer. 2. CYTOPLASM Structure - The jelly-like substance composed of mainly water and found between the cell membrane and nucleus. The cytoplasm makes up most of the "body" of a cell and is constantly streaming. Function - Organelles are found here and substances like salts may be dissolved in the cytoplasm. 3. NUCLEUS Structure - The largest organelle in the cell. It is dark and round, and is surrounded by a double membrane called the nuclear envelope/membrane. In spots the nuclear envelope fuses to form pores which are selectively permeable. The nucleus contains genetic information (DNA) on special strands called chromosomes. Function - The nucleus is the "control center" of the cell, for cell metabolism and reproduction. 1. "ER" OR ENDOPLASMIC RETICULUM The Endoplasmic Reticulum is a network of membranous canals filled with fluid. They carry materials throughout the cell. The ER is the "transport system" of the cell. There are two types of ER: rough ER and smooth ER. Rough Endoplasmic Reticulum is lined with ribosomes and is rough in appearance and smooth endoplasmic reticulum contains no ribosomes and is smooth in appearance. 2. RIBOSOMES Ribosomes are small particles which are found individually in the cytoplasm and also line the membranes of the rough endoplasmic reticulum. Ribosomes produce protein. They could be thought of as "factories" in the cell. 3. GOLGI BODY / APPARATUS Golgi bodies are stacks of flattened membranous stacks (they look like pancakes!). The Golgi Body temporarily stores protein which can then leave the cell via vesiciles pinching off from the Golgi. 4. LYSOSOMES Lysosomes are small sac-like structures surrounded by a single membrane and containing strong digestive enzymes which when released can break down worn out organelles or food. The lysosome is also known as a suicide sac. 5. MITOCHONDRIA The mitochondria are round "tube-like" organelles that are surrounded by a double membrane, with the inner membrane being highly folded. the mitochondria are often referred to as the "powerhouse" of the cell. the mitochondria releases food energy from food molecules to be used by the cell. This process is called respiration. Some cells( muscle cells) require more energy than other cells and so would have many more mitochondria. 6. VACUOLES Vacuoles are fluid filled organelles enclosed by a membrane. They can store materials such as food, water, sugar, minerals and waste products ORGANELLES AND OTHER FEATURES FOUND ONLY IN PLANT CELLS: 1. CELL WALL The cell wall is a rigid organelle composed of cellulose and lying just outside the cell membrane. The cell wall gives the plant cell it's box-like shape. it also protects the cell. The cell wall contains pores which allow materials to pass to and from the cell membrane. 2. PLASTIDS Plastids are double membrane bound organelles. It is in plastids that plants make and store food. Plastids are found in the cytoplasm and there are two main types: Leucoplasts - colorless organelles which store starch or other plant nutrients. ( example - starch stored in a potato) Chromoplasts - contain different colored pigments. The most important type of chromoplast is the chloroplast, which contains the green pigment chlorophyll. This is important in the process of photosynthesis. 3. CENTRAL VACUOLE The central vacuole is a large fluid-filled vacuole found in plants

Similarities between prokaryotes and eukaryotes

1. They both have DNA as their genetic material. 2. They are both membrane bound. 3. They both have ribosomes . 4. They have similar basic metabolism . 5. They are both amazingly diverse in forms

What is tissue?

A cellular organizational level intermediate between cells and a complete organ. A tissue is an ensemble of similar cells from the same origin that together carry out a specific function. Organs are then formed by the functional grouping together of multiple tissues.

Homologues?

A chromosome that is similar in physical attributes and genetic information to another chromosome with which it pairs during meiosis. A member of homologous chromosome. Homologue chromosomes are two chromosomes that have the same size, shape, centromere position, and equivalent loci.

Reading codons and what amino acids match.

A codon is a sequence of three DNA or RNA nucleotides that corresponds with a specific amino acid or stop signal during protein synthesis. In DNA, A and T pair up and G and C pair up. For example. ATG -> TAC. However, with RNA, A pairs up with U. For example, UTA -> AAT

Function of flagella?

A flagellum is a whip-like structure that allows a cell to move. They are found in all three domains of the living world: bacteria, archaea, and eukaryota, also known as protists, plants, animals, and fungi. While all three types of flagella are used for locomotion, they are structurally very different. These are "nano motors" giving the cell mobility. In prokaryotes (bacteria), the flagellum is a "rotary engine" driven by a proton concentration gradient Eukaryote flagella (and cilia, in stationary cells facilitating material transport) work more like "whips" (reciprocal motion), made from a bundle of microtubules, driven by the "motor protein" dynein, fueled by ATP

Co-dominant?

A form of dominance in which the alleles of a gene pair in a heterozygote are fully expressed thereby resulting in offspring with a phenotype that is neither dominant nor recessive In genetics, dominance pertains to the property of a gene (or allele) in relation to other genes or alleles. A gene or allele shows dominance when it suppresses the expression, or dominates the effects, of the recessive gene (or allele). There are many forms of dominance: complete dominance, incomplete dominance, and codominance. Codominance is a form of dominance wherein the alleles of a gene pair in a heterozygote are fully expressed. This results in offspring with a phenotype that is neither dominant nor recessive. A typical example showing codominance is the ABO blood group system. For instance, a person having A allele and B allele will have a blood type AB because both the A and B alleles are codominant with each other. Codominance is different from incomplete dominance in a way that the former has both alleles manifesting the phenotypes whereas the latter produces an intermediate phenotype.

What is an organ system?

A group of organs that work together to carry out a particular task. A biological unit of the body or of an organism. Examples of systems in human body: • Circulatory system • Digestive system • Endocrine system • Integumentary system • Lymphatic system • Muscular system • Nervous system • Reproductive system • Respiratory system • Skeletal system • Urinary system

What is an organ?

A group of tissues that perform a specific function or group of functions. Examples of animal organs are heart, lungs, brain, eye, stomach, spleen, bones, pancreas, kidneys, liver, intestines, skin, urinary bladder and sex organs. Examples of plant organs are the roots, stems, leaves, flowers, seeds and fruits.

Homozygous vs heterozygous?

A heterozygous individual is someone who has two different alleles at a locus. For instance, using the sickle cell example, a heterozygous individual might have a genotype of AS. A homozygous individual has two identical alleles at a locus. The genotype for a homozygous individual might be AA or SS. Heterozygous: It is pure for a trait and breeds true i.e., gives rise to similar homozygous individuals Both alleles of a trait are similar, e.g., TT, tt Homozygous individual can carry either dominant or recessive alleles but not both It produces one type of gamaetes It does not show extra vigour Homozygous: Heterzygous individual is seldom pure and produces offspring with different genotypes on selfing, eg., TT, Tt and tt on selfing of Tt individuals It carries dissimilars alleles, e.g., Tt Heterozygous individual has both dominant and recessive alleles It produces two type of gametes The individual can show extra vigour called hybrid vigour or heterosis

What is passive diffusion?

A kind of transport by which ions or molecules move along a concentration gradient, which means movement from an area of higher concentration to an area of lower concentration. Since the movement of substances is by passive transport, this process does not require chemical energy (in contrast to active transport). In moving substances across a biological membrane, a passive transport may or may not need the assistance of a membrane protein. There are four major types of passive transport: simple diffusion facilitated diffusion filtration osmosis

What is active transport?

A kind of transport wherein ions or molecules move against a concentration gradient, which means movement in the direction opposite that of diffusion - or - movement from an area of lower concentration to an area of higher concentration. Hence, this process will require expenditure of energy, and the assistance of a type of protein called a carrier protein. The movement of a substance across a membrane from a region of its lower concentration to a region of its higher concentration against a concentration gradient, using energy. This energy is supplied through respiration using ATP. Mitochondria ( cell organelles in the cytoplasm) control energy release. Respiratory poisons block energy release, so they can prevent active transport. Common sites of active transport are root hair cells the wall of small intestine

What is an organelle?

A membrane-bound compartment or structure in a cell that performs a special function

Crossing-Over?

A process occurring during meiosis wherein homologous chromosomes pair up and exchange segments of their genetic material Chromosomal crossover occurs when homologous chromosomes exchange genetic material. This occurs at the stage when chromatids of homologous chromosomes pair up during synapsis, forming X-structure (chiasma). The chromatids break into segments (of matching regions), which are then exchanged with one another. The result in recombinant chromosomes. It particularly occurs in the pachytene stage of prophase I of the first meiotic division. Chromosomal crossover generally occurs when segments on homologous chromosomes break, and then, reconnect to the other of the matching chromosome. This was first demonstrated in 1931 by Harriet Creighton and Barbara McClintock. Chromosomal crossover between homologous chromosomes is important because it results in new combinations of genes that are different from either parent, contributing to genetic diversity. Chromosomal crossover resulting in exchanges o unequal amounts of genetic material due to sequence mismatch may occur but not often. When this happens, it is termed as a non-homologous crossover or an unequal crossover. This results in an insertion or deletion mutation.

What is a centriole?

A self-replicating, small, fibrous, cylindrical-shaped organelle, typically located in the cytoplasm near the nucleus in cells of most animals. It is involved in the process of nuclear division. The centriole contains nine pairs of peripheral microtubules arranged orthogonally so as to form the wall of the cylinder. The centrioles are absent in higher plants and most fungi.

Mitochondria

A spherical or rod-shaped organelle with its own genome, and is responsible for the generation of most of the cell's supply of adenosine triphosphate through the process of cellular respiration The mitochondrion is regarded as the powerhouse of eukaryotic cells. That is because it is the organelle that supplies energy by generating adenosine triphosphate (ATP) through cellular respiration. The mitochondrion consists of outer and inner membranes, an intermembrane space (space in between the membranes), the cristae (infoldings of the inner membrane), and the matrix (space within the inner membrane). The outer membrane contains several porins that form channels where certain molecules can freely diffuse. Unlike the outer membrane, the inner membrane does not contain porins and is highly impermeable to all molecules. Most ions and molecules would need special membrane transporters to enter or exit the matrix. The cristae, which are the foldings of the inner membrane, increase the surface area thereby increasing ATP production. The matrix contains enzymes, mitoribosomes, tRNA, and DNA. The mitochondrial DNA is genetically distinct from that in the nucleus. Since a mitochondrion has its own genetic material, and is capable of manufacturing its own RNAs and proteins, it is said to be a semi-autonomous, self-reproducing structure. In fact, the mitochondrial DNA has become an important tool in tracking genetic histories since the genetic material is present in only one copy, and does not recombine during reproduction. It produces large amounts of energy through oxidative phosphorylation of organic molecules during cellular respiration. It is capable of using glucose and oxygen to produce energy (and releasing carbon dioxide and water in the process) for use in many metabolic processes. Thus, it is not surprising to find several mitochondria in high energy-requiring cells, such as muscle cells. There are cells that lack mitochondrion, such as mature red blood cells of mammals. It is thought that the mitochondria might have originated from early bacteria that became so symbiotic with their hosts, the eukaryotic cells, that they evolved and become indispensable energy-yielding structures within the eukaryotic cells (endosymbiotic theory). Nevertheless, there is a eukaryote that lacks mitochondrion. Monocercomonoides is the first eukaryotic species found to be devoid of mitochondria, and obtains energy by metabolizing nutrients absorbed from the environment.

True-breeding?

A true-breeding organism, sometimes also called a purebred, is an organism that always passes down certain phenotypic traits (i.e. physically expressed traits) to its offspring. An organism is referred to as true breeding for each trait to which this applies, and the term "true-breeding" is also used to describe individual genetic traits. In Mendelian genetics, this means that an organism must be homozygous for every trait for which it is considered true breeding; that is, the pairs of alleles that express a given trait are the same. In a purebred strain or breed, the goal is that the organism will "breed true" for the breed-relevant traits. Types of asexual reproduction, also result in true breeding, although the organisms are usually not homozygous

How are active transport, facilitated diffusion, and passive diffusion similar?

Allow the cell to maintain homeostasis by maintaining an equilibrium of substances in and out of the cell. Involve moving material across or through the plasma membrane Involve ion movement. Use ion channels to move ions across the cell membrane, in or out of the cell.

What is an organism?

An individual living thing that can react to stimuli, reproduce, grow, and maintain homeostasis. It can be a virus, bacterium, protist, fungus, plant or an animal.

Organelles found in prokaryotic cells and functions

Cell wall: -surrounds the plasma membrane -gives the cell its shape -prevents bursting when turgid pressure is high -helps anchor appendages like pili and flagella -composed of cellulose microfibers which form a thick wall -grows with the cell -helps the cell maintain osmotic balance Plasma membrane: -encloses the interior of the cell -regulates the flow of material in and out of the cell Cytoplasm: -carries out functions for all growth, metabolism and replication -composed of water, enzymes and nutrients, wastes and gasses -gel-like matrix -contains cells structures (such as ribosome) Ribosomes: -translates the genetic code from the DNA to make proteins (proteins are molecules that perform all the functions of cells and living organisms) -composed of 2 subunits -can be found free floating in cytoplasm Nucleoid: -not a membrane bound nucleus -an area of the cytoplasm where the strands of DNA are found Pili: -small hairlike projections emerging from the outside cell surface -assists in the cell attaching to other cells and surfaces DNA: the genetic material of the cell

Diploid vs haploid?

Diploid: Diploid cells contain two complete sets (2n) of chromosomes. Diploid cells reproduce by mitosis making daughter cells that are exact replicas. Skin, blood, muscle cells (also known as somatic cells) Haploid: Haploid cells have half the number of chromosomes (n) as diploid - i.e. a haploid cell contains only one complete set of chromosomes. Haploid cells are a result of the process of meiosis, a type of cell division in which diploid cells divide to give rise to haploid germ cells. A haploid cell will merge with another haploid cell at fertilization. Cells used in sexual reproduction, sperm and ova (also known as Gametes).

Dominant vs recessive

Dominant: When an allele is dominant, the characteristic it is connected to will be expressed in sexually-reproduced offspring. (typically shown as an upper case letter in Punnett squares) Recessive: When an allele is recessive, the characteristic it is connected to is less likely to be expressed. Recessive traits only manifest when both parents carry a recessive trait or have fully recessive traits to pass down. (typically shown as a lower case letter in Punnett squares) In the picture: The A would be the dominant trait and the a would be the recessive trait

Chromosomes of prokaryotes?

Found in cytoplasm Circular chromosome attached to inside of cell membrane Single chromosome plus plasmids Made only of DNA Copies its chromosome and divides

Chromosomes of eukaryotes?

Found in nucleus Linear chromosomes Many chromosomes Usually 10-59 chromosomes in somatic cells Human body cells have 46 chromosomes Made of chromatin, a nucleoprotein (DNA coiled around histone proteins) Copies chromosomes, then the cell grows (G2 phase), then goes through mitosis to organize chromosomes in two equal groups

What are the jobs of mRNA?

Messenger RNA (mRNA) carries the genetic information copied from DNA in the form of a series of three-base code "words," each of which specifies a particular amino acid Each molecule, or chain, of mRNA carries instructions on how to connect several "amino acids" into a peptide chain, which becomes a protein. The same way that nucleotides are building blocks for RNA, amino acids are building blocks for proteins. Evolution has produced a "genetic code" wherein each of life's 20 amino acids is coded for by a series of three nitrogenous bases in RNA nucleotides. Thus, each triplet of RNA nucleotides corresponds to one amino acid, and the sequence of nucleotides dictates the sequence of amino acids that will be linked into the peptide chain that makes a protein. While in some cases an amino acid can be represented by multiple nucleotide triplets, called codons, each codon on RNA represents only one amino acid. For this reason, the genetic code is said to be "degenerate." During translation, a strand of mRNA passes through a ribosome, like an old-fashion cassette tape moving through a tape reader

Monohybrid vs Dihybrid

Monohybrid: It is a cross between two pure organisms in order to study the inheritance of a single pair of alleles. It produces a phenotype monohybrid ratio of 3:1 in F2 generation It produces genotype ratio of 1:2:1 in F2 Test cross ratio - 1:1 Dihybrid: It is a cross between two pure organisms of a species in order to study the inheritance of two pairs of alleles belonging to two different characters It produces a phenotype dihybrid ratio of 9:3:3:1 in F2 It produces genotypic ratio of 1:2:1:2:4:2:1:2:1 Test cross ratio - 1:1:1:1 A monohybrid cross is when the offspring of homozygous parents that only differ on a single trait are bred to come up with the second generation. On the other hand, a dihybrid cross is pretty similar to a monohybrid cross except that the parents of the first generation differ in two traits

An error in DNA replication can cause?

Mutations, genetic variation, and cancer.

Organelles found in eukaryotic cells and functions:

Plasma membrane: -encloses the interior of the cell -regulates the flow of material in and out of the cell Cytoplasm: -carries out functions for all growth, metabolism and replication -composed of water, enzymes and nutrients, wastes and gasses -gel-like matrix -contains cells structures (such as ribosome) Ribosomes: -translates the genetic code from the DNA to make proteins (proteins are molecules that perform all the functions of cells and living organisms) -composed of 2 subunits -can be found in the mitochondria and the chloroplast Endoplasmic Reticulum: -an extensive network of channels that stretches from the nucleus to the plasma membrane -function is to transport materials through the cell -ROUGH ER - distinguished by the ribosomes attached to it -SMOOTH ER- many functions such as production of membrane phospholipids, production of sex hormones, breaks down harmful substances, stores calcium ions, transports liquid based compounds, and aids liver cells in releasing glucose into the blood when needed Lysosomes: -single membrane bound organelle produced by the GOLGI APPARATUS that contain strong hydraulic enzymes which break down biological molecules -contains up to 40 different enzymes -breaks down worn out cell parts that are no longer functioning properly -involved in breaking down materials brought into a cell VIA phagocytosis Golgi Apparatus: -composed of many flattened sacs called cisternae, which are stacked on top of each other -normally located between the ER and plasma membrane -it collects, packages, modifies, and distributes materials throughout the cell -found in high numbers in cells that produce and secrete substances Mitochondria: -very large, double membrane bound rod-shaped organelles found scattered in the cytoplasm and contain their own DNA -other membrane is smooth -inner membrane is highly folded into cristane which increases the surgace area for cellular respiration, which is the main function of the mitochondria -found in high numbers in cells that have high energy needs (EX: muscle cells) -known as the "power house" of the cell Nucleus -where DNA is housed -has a double membrane that allows the DNA to remain separate from the rest of the cell and can carry out its functions without interference from the other parts of the cell -nuclear membrane contains pores that allows for communication with the rest of the cell -DNA is contained here in the form of chromosomes -normally located in the center of the cell -most cells have only 1 nucleus, but some have multiple nuclei, while others have none (EX: Red Blood Cells) -if a nucleus is not present, that cell cannot reproduce -most nuclei have a nucleolus, a dark area inside the nucleus where ribosomes are made

Characteristics of prokaryotic cells

Prokaryotes lack an organized nucleus and other membrane-bound organelles. Prokaryotic DNA is found in a central part of the cell called the nucleoid. The cell wall of a prokaryote acts as an extra layer of protection, helps maintain cell shape, and prevents dehydration. Prokaryotic cell size ranges from 0.1 to 5.0 μm in diameter. The small size of prokaryotes allows quick entry and diffusion of ions and molecules to other parts of the cell while also allowing fast removal of waste products out of the cell. A prokaryote is a simple, single-celled (unicellular) organism that lacks an organized nucleus or any other membrane-bound organelle. We will shortly come to see that this is significantly different in eukaryotes. Prokaryotic DNA is found in a central part of the cell: the nucleoid . Most prokaryotes have a peptidoglycan cell wall and many have a polysaccharide capsule . The cell wall acts as an extra layer of protection, helps the cell maintain its shape, and prevents dehydration. The capsule enables the cell to attach to surfaces in its environment. Some prokaryotes have flagella, pili, or fimbriae. Flagella are used for locomotion. Pili are used to exchange genetic material during a type of reproduction called conjugation. Fimbriae are used by bacteria to attach to a host cell. According to quizlet: Bacterial organisms, smaller (microscopic), no organelles (no nucleus), older, unicellular

What are the jobs of RNA?

RNA carries out the instructions encoded in DNA Three kinds of RNA molecules perform different but cooperative functions in protein synthesis The three roles of RNA in protein synthesis. Messenger RNA (mRNA) is translated into protein by the joint action of transfer RNA (tRNA) and the ribosome, which is composed of numerous proteins and two major ribosomal RNA (rRNA) molecules. RNA plays an active role in transcribing and translating genes and proteins that make up the human body

Results of meoisis

Results in four daughter cells Results in haploid daughter cells (chromosome number is halved from the parent cell) Daughter cells are genetically different At the end of this, the cell undergoes cytokinesis, with each daughter cell being haploid, having only one set of chromosomes. In other words, it has only half the genetic material of the parent cell, setting the stage for crucial genetic shuffling once fertilisation occurs. Meiosis completes after a second stage, meiosis II, which is mechanically fairly identical to mitosis. Meiosis: One diploid cell → four haploid cells. Goal is genetic shuffling and production of gametes.

Ribosome?

Ribosomes are the protein builders or the protein synthesizers of the cell. Ribosomes link amino acids together in the order specified by messenger RNA (mRNA) molecules. Ribosomes consist of two major components: the small ribosomal subunit, which reads the RNA, and the large subunit, which joins amino acids to form a polypeptide chain. Each subunit is composed of one or more ribosomal RNA (rRNA) molecules and a variety of ribosomal proteins

Stop Codon?

Stop codons signal the end of the polypeptide chain during translation. These codons are also known as nonsense codons or termination codons as they do not code for an amino acid. There are 3 stop codons in the genetic code- UAG, UAA, and UGA.

Cell growth is limited by its?

Surface area

Plasma membrane function

The biological membrane, which is present in both eukaryotic and prokaryotic cell. It is also called as cell membrane as it is works as a barrier between the inner and outer surface of a cell. In animal cells, the plasma membrane is present in the outer most layer of the cell and in plant cell it is present just beneath the cell wall. It separates the contents of the cell from its outside environment and it regulates what enters and exits the cell. Plasma membrane plays a vital role in protecting the integrity of the interior of the cell by allowing only selected substances into the cell and keeping other substances out. It also serves as a base of attachment for the cytoskeleton in some organisms and the cell wall in others. Thus the cell membrane supports the cell and helps in maintaining the shape of the cell. The cell membrane is primarily composed of proteins and lipids. While lipids help to give membranes their flexibility and proteins monitor and maintain the cell's chemical climate and assist in the transfer of molecules across the membrane. The lipid bilayer is semi-permeable, which allows only selected molecules to diffuse across the membrane.

Why is surface area important in limiting cell growth?

The cell may become too large to take in enough food and to remove enough waste.

All cells have what?

The common features of prokaryotic and eukaryotic cells are: DNA, the genetic material contained in one or more chromosomes and located in a nonmembrane bound nucleoid region in prokaryotes and a membrane-bound nucleus in eukaryotes Plasma membrane, a phospholipid bilayer with proteins that separates the cell from the surrounding environment and functions as a selective barrier for the import and export of materials Cytoplasm, the rest of the material of the cell within the plasma membrane, excluding the nucleoid region or nucleus, that consists of a fluid portion called the cytosol and the organelles and other particulates suspended in it Ribosomes, the organelles on which protein synthesis takes place

How does concentration change with diffusion and osmosis?

The concentration will equal out because of diffusion and osmosis, because the goal of diffusion and osmosis is to reach equilibrium.

Why would a cell need to change shape?

The environments in which cells grow often change rapidly. To survive in a changing world, cells evolved mechanisms for adjusting their biochemistry in response to signals indicating environmental change The cytoplasm of the cell is made of proteins and these proteins have two levels of being connected together. If an area of the cell under the cell membrane needs to move, like when forming an endocytic vesicle, the cytoplasm there changes from a state of being bit solid to a state of being a bit liquid. This is called (gel to sol)l transformation.Gel is for gelatin and sol if for solution. This sol cytoplasm under the membrane enables the membrane to go inside a little so the vesicle can start forming. Once the vesicle is in, the cytoplasm under the cell membrane goes back to the gel state. This transformation from gel to sol and vice versa is what explains the change in cell shape, and of course the significance is for the cell to interact with the surrounding by getting its needs or defending itself

What is diffusion?

The passive movement of molecules or particles along a concentration gradient, or from regions of higher to regions of lower concentration. It is a type of passive transport, therefore, it is a net movement of molecules in and out of the cell across the cell membrane along a concentration gradient. Unlike active transport, diffusion does not involve chemical energy. When molecules move (diffuse) via special transport proteins found within the cell membrane, it is called facilitated diffusion, otherwise it is only simple diffusion. An example of diffusion in biological system is diffusion of oxygen and carbon dioxide across the alveolar-capillary membrane in mammalian lungs. Diffusion may be a simple diffusion or facilitated diffusion. A simple diffusion is one in which that occurs unassisted. Facilitated diffusion in contrast is an assisted diffusion in a way that it requires a carrier molecule. For instance, polar molecules diffuse across a cell membrane through carrier molecules embedded in the cell membrane.

What is a centromere?

(1) The constricted region joining the two sister chromatids that make up an X-shaped chromosome. (2) The site where kinetochore is formed. Centromere is important particularly during mitosis. Aside from being the region where chromatids are held and kinetochore is formed, it also serves as the point of attachment for spindle fibers when the spindle fibers are pulling the chromosomes toward the centrioles (situated on opposite poles in a cell) prior to cytokinesis. When the centromere is not functioning properly, the chromatids do not align and separate properly, thus, resulting in the wrong number of chromosomes in the daughter cells, and conditions such as Down syndrome.

What is osmosis?

1. Diffusion of a solvent (usually water molecules) through a semipermeable membrane from an area of low solute concentration to an area of high solute concentration. 2. Net movement of water molecules through a semipermeable membrane from an area of higher water potential to an area of lower water potential. 3. Tendency of water to flow from a hypotonic solution (low concentration of dissolved substances) to hypertonic solution (higher concentration of dissolved substances) across a semipermeable membrane In biological systems, osmosis is essential since many biological membranes are semipermeable, and it leads to different physiological effects. For example, when an animal cell is exposed to a hypertonic surrounding (or lower water concentration) the water will leave the cell causing the cell to shrink. When an animal cell is placed in a hypotonic surrounding (or higher water concentration), the water molecules will move into the cell causing the cell to swell. If osmosis continues and becomes excessive the cell will eventually burst. In a plant cell, excessive osmosis is prevented due to the osmotic pressure exerted by the cell wall thereby stabilizing the cell. In fact, osmotic pressure is the main cause of support in plants. However, if a plant cell is placed in a hypertonic surrounding, the cell wall cannot prevent the cell from losing water. It results in cell shrinking (or cell becoming flaccid).

What organelles are found in animal cells?

1. PLASMA MEMBRANE/ CELL MEMBRANE Structure- a bilipid membraneous layer composed of proteins and carbohydrates. It is fluid like. Function - the cell membrane separates the cell from its external environment, and is selectively permeable (controls what gets in and out). It protects the cell and provides stability. Proteins are found embedded within the plasma membrane, with some extending all the way through in order to transport materials. Carbohydrates are attached to proteins and lipids on the outer lipid layer. 2. CYTOPLASM Structure - The jelly-like substance composed of mainly water and found between the cell membrane and nucleus. The cytoplasm makes up most of the "body" of a cell and is constantly streaming. Function - Organelles are found here and substances like salts may be dissolved in the cytoplasm. 3. NUCLEUS Structure - The largest organelle in the cell. It is dark and round, and is surrounded by a double membrane called the nuclear envelope/membrane. In spots the nuclear envelope fuses to form pores which are selectively permeable. The nucleus contains genetic information (DNA) on special strands called chromosomes. Function - The nucleus is the "control center" of the cell, for cell metabolism and reproduction. 1. "ER" OR ENDOPLASMIC RETICULUM The Endoplasmic Reticulum is a network of membranous canals filled with fluid. They carry materials throughout the cell. The ER is the "transport system" of the cell. There are two types of ER: rough ER and smooth ER. Rough Endoplasmic Reticulum is lined with ribosomes and is rough in appearance and smooth endoplasmic reticulum contains no ribosomes and is smooth in appearance. 2. RIBOSOMES Ribosomes are small particles which are found individually in the cytoplasm and also line the membranes of the rough endoplasmic reticulum. Ribosomes produce protein. They could be thought of as "factories" in the cell. 3. GOLGI BODY / APPARATUS Golgi bodies are stacks of flattened membranous stacks (they look like pancakes!). The Golgi Body temporarily stores protein which can then leave the cell via vesiciles pinching off from the Golgi. 4. LYSOSOMES Lysosomes are small sac-like structures surrounded by a single membrane and containing strong digestive enzymes which when released can break down worn out organelles or food. The lysosome is also known as a suicide sac. 5. MITOCHONDRIA The mitochondria are round "tube-like" organelles that are surrounded by a double membrane, with the inner membrane being highly folded. the mitochondria are often referred to as the "powerhouse" of the cell. the mitochondria releases food energy from food molecules to be used by the cell. This process is called respiration. Some cells( muscle cells) require more energy than other cells and so would have many more mitochondria. 6. VACUOLES Vacuoles are fluid filled organelles enclosed by a membrane. They can store materials such as food, water, sugar, minerals and waste products. ANIMAL CELLS ORGANELLES NOT FOUND IN PLANT CELLS: CILIA AND FLAGELLA Both cilia and flagella are hair-like organelles which extend from the surface of many animal cells. the structure is identical in both, except that flagella are longer and whiplike and cilia are shorter. There are usually only a few flagella on a cell, while cilia may cover the entire surface of a cell. The function of cilia and flagella ionclude locomotion for one-celled organisms and to move substances over cell surfaces in multi-celled organisms.

What is a solute?

1. a component of a solution: in a solution, the dissolving substance is called a solvent whereas the dissolved substance is called a solute 2. a substance (usually in lesser] amount) dissolved in another substance. A typical example of a solution is sugar dissolved in water: sugar is the solute and water is the solvent

What is the purpose of meiosis?

1. to produce gametes for sexual reproduction 2. to reduce chromosome # because fertilization will double it --> genetic variation The purpose of meiosis is to reduce the normal diploid cells (2 copies of each chromosome / cell) to haploid cells, called gametes (1 copy of each chromosome per cell). In humans, these special haploid cells resulting from meiosis are eggs (female) or sperm (male).

Incomplete dominance?

A form of dominance occurring in heterozygotes in which the dominant allele is only partially expressed, and usually resulting in an offspring with an intermediate phenotype In genetics, dominance pertains to the property of a gene (or allele) in relation to other genes or alleles. A gene or allele shows dominance when it suppresses the expression, or dominates the effects, of the recessive gene (or allele). There are many forms of dominance: complete dominance, incomplete dominance, and codominance. In incomplete dominance, a heterozygous organism carrying two alleles wherein one is dominant and the other one is recessive, (e.g. Aa), the dominant allele will only be partially expressed. Hence, the heterozygote (Aa) will have an intermediate phenotype. A typical example is the color of the flower in which R symbolizes the dominant allele for red pigment and r is the recessive allele for no pigment. In incomplete dominance, the heterozygous plant carrying both alleles, Rr, will not be able to produce enough red pigment (since the dominant allele is only partially expressed) and therefore will appear pink

Complete dominance?

A form of dominance wherein the dominant allele completely masks the effect of the recessive allele in heterozygous condition In genetics, dominance pertains to the property of a gene (or allele) in relation to other genes or alleles. A gene or allele shows dominance when it suppresses the expression, or dominates the effects, of the recessive gene (or allele). There are many forms of dominance: complete dominance, incomplete dominance, and codominance. Complete dominance is a form of dominance in heterozygous condition wherein the allele that is regarded as dominant completely masks the effect of the allele that is recessive. For instance, an individual carrying two alleles that are both dominant (e.g. AA), the trait that they represent will be expressed. But if the individual carries two alleles in a manner that one is dominant and the other one is recessive, (e.g. Aa), the dominant allele will be expressed while the recessive allele will be suppressed. Hence, the heterozygote (Aa) will have the same phenotype as that of the dominant homozygote (AA). This condition is called complete dominance. When the dominance is not complete, it is referred to as incomplete dominance. In this form of dominance, the dominant allele is only partially expressed. The result is a heterozygote (Aa) with an intermediate phenotype. In another form of dominance, i.e. codominance, the alleles of a gene pair in a heterozygote are fully expressed. This results in offspring with a phenotype that is neither dominant nor recessive.

How are active transport, facilitated diffusion, and passive diffusion different?

Active transport: Energy-requiring process that moves material across a cell membrane against the concentration gradient. Moves molecules, atoms, ions, etc. from an area of high concentration to an area of low concentration. Passive diffusion: Movement of molecules across the cell membrane from kinetic energy from molecular motion. Moves molecules, atoms, ions, etc. from an area of low concentration to an area of high concentration. Facilitated diffusion: A type of passive transport, lets larger molecules enter the cell membrane, uses a protein channel or carrier molecule to move the molecule, ion, etc. (Ex. movement of glucose through a cell membrane) Easy to understand: Active transport requires energy, passive diffusion does not and facilitated diffusion is a type of passive diffusion

Explain Cellular Respiration

Cellular respiration is the process of extracting energy in the form of ATP from the glucose in the food you eat. How does cellular respiration happen inside of the cell? Cellular respiration is a three step process. Briefly: In stage one, glucose is broken down in the cytoplasm of the cell in a process called glycolysis. In stage two, the pyruvate molecules are transported into the mitochondria. The mitochondria are the organelles known as the energy "powerhouses" of the cells. In the mitochondria, the pyruvate, which have been converted into a 2-carbon molecule, enter the Krebs cycle. Notice that mitochondria have an inner membrane with many folds, called cristae. These cristae greatly increase the membrane surface area where many of the cellular respiration reactions take place. In stage three, the energy in the energy carriers enters an electron transport chain. During this step, this energy is used to produce ATP. Oxygen is needed to help the process of turning glucose into ATP. The initial step releases just two molecules of ATP for each glucose. The later steps release much more ATP. The Reactants What goes into the cell? Oxygen and glucose are both reactants of cellular respiration. Oxygen enters the body when an organism breathes. Glucose enters the body when an organism eats. The Products What does the cell produce? The products of cellular respiration are carbon dioxide and water. Carbon dioxide is transported from your mitochondria out of your cell, to your red blood cells, and back to your lungs to be exhaled. ATP is generated in the process. When one molecule of glucose is broken down, it can be converted to a net total of 36 or 38 molecules of ATP. This only occurs in the presence of oxygen.

Flagella vs cilia?

Cilia and flagella are cell organelles that are structurally similar but are differentiated based on their function and/or length. Cilia are short and there are usually many (hundreds) cilia per cell. On the other hand, flagella are longer and there are fewer flagella per cell (usually one to eight). Though eukaryotic flagella and motile cilia are structurally identical, the beating pattern of the two organelles can be different. The motion of flagella is often undulating and wave-like, whereas the motile cilia often perform a more complicated 3D motion with a power and recovery stroke Cilia: Definition: Cilia are short, hair like appendages extending from the surface of a living cell. Cross section: Nexin arm present. Length: Short Motion: Rotational, like a motor, very fast moving Density: Many (hundreds) per cell Found in: Eukaryotic cells Flagella: Definition Flagella are long, threadlike appendages on the surface of a living cell. Cross section: Nexin arm absent . Length:Longer than cilia, can vary Motion:Wave-like, undulating, sinusoidal, slow movement compared to cilia Density:Few (less than 10) per cell Found in: Eukaryotic and prokaryotic cells

Function of cilia?

Cilia are microscopic, hair-like structures that extend outwardfrom the surface of manyanimal cells. These structures are important in the cell cycle and replication, and cilia play a vital part in human and animal development and in everyday life. A typical cilium is between one and ten micrometers long, and usually less than one micrometer wide. They are often divided into two different types, and these types can work together or separately. They types are motile and non-motile. Motile cilia, which means "moving," can be found in the respiratory tract, middle ear, and other body systems. Multiple cilia willwave in a rhythmic or pulsating motion, and use that motion to keep sensitive internal passagewaysfree of mucus or foreign particles, for example. Body cells that have a single moving cilium are sperm cells, which use that cilium to propel the cell. The non-motile cilia play a crucial role in many different organs. Some serve almost like antenna that receive sensory information for the cell, processing signals from the other cells or the fluids surrounding it. For example, cilia in the kidney are forced to bend as urine flows past, which sends signals to the cells that it is flowing. Non-motile cilia inside the eye are housed in the retina's photoreceptors, allowingimportant molecules to be transported from one end to the other.

DNA structure

DNA is made up of molecules called nucleotides. Each nucleotide contains a phosphate group, a sugar group and a nitrogen base. The four types of nitrogen bases are adenine (A), thymine (T), guanine (G) and cytosine (C). The order of these bases is what determines DNA's instructions, or genetic code. Similar to the way the order of letters in the alphabet can be used to form a word, the order of nitrogen bases in a DNA sequence forms genes, which in the language of the cell, tells cells how to make proteins. Another type of nucleic acid, ribonucleic acid, or RNA, translates genetic information from DNA into proteins. Nucleotides are attached together to form two long strands that spiral to create a structure called a double helix. If you think of the double helix structure as a ladder, the phosphate and sugar molecules would be the sides, while the bases would be the rungs. The bases on one strand pair with the bases on another strand: adenine pairs with thymine, and guanine pairs with cytosine. DNA molecules are long — so long, in fact, that they can't fit into cells without the right packaging. To fit inside cells, DNA is coiled tightly to form structures we call chromosomes. Each chromosome contains a single DNA molecule. Humans have 23 pairs of chromosomes, which are found inside the cell's nucleus.

Replication?

DNA replication is the process by which DNA makes a copy of itself during cell diversion. Using one DNA molecule, two identical replicas of DNA are produced. Producing two identical copies of a DNA molecule is essential for cell division during growth or repair of damaged tissues. DNA replication ensures that each new cell receives its own copy of the DNA. DNA replication takes place in the nucleus of eukaryotic cells and in the cytoplasm of prokaryotic cells. DNA replication occurs during the synthesis-phase portion of the interphase. Interphase occurs between cell divisions and is a necessary precursor step for cell division. ​First, an enzyme called helicase breaks apart the hydrogen bonds that hold the strands of DNA together, resulting in the DNA "unzipping" and separating into a replication fork. There are two strands, the leading strand- oriented towards the replication fork- and the lagging strand- oriented away from the replication fork. An enzyme called DNA polymerase adds new nucleotides to both strands. The nucleotides pair with the complementary nucleotides on the already existing strand (A with T, G with C). Then, an enzyme called DNA ligase seals up the fragments into one continuous strand. Finally, the new copies with automatically wind up again. Adding nucleotides to both strands is why two replicas are produced from one DNA molecule.

Law of segregation?

Each inherited trait is defined by a gene pair. Parental genes are randomly separated to the sex cells so that sex cells contain only one gene of the pair. Offspring therefore inherit one genetic allele from each parent when sex cells unite in fertilization.

Why do solutions want to be at equilibrium?

Equilibrium state is the state in which the concentration of the contents inside the cell is equal to that on the outside. The phenomenon which takes place when the solute molecules move from higher concentration to lower concentration is known as osmosis. The reverse of this also takes place which is known as reverse osmosis. This osmosis takes place when there is no equilibrium between the outside and inside of the cell membrane. The maintenance of this phenomenon inter and intra cellularly is very necessary for the cells to survive.

Phases of meiosis

Meiosis • Meiosis will allow the chromosome number to remain constant throughout the generations • Provides for genetic variation • Meiosis can be broken into two parts: Meiosis I and Meiosis II • Meiosis I separates homologous c-somes • Meiosis II is essentially a mitotic division and the sister chromatids separate • Meiosis halves the number of chromosomes Meiosis I • Prophase I: Homologous c-somes condense; crossing-over takes place (a source of variation); nuclear envelope breaks down • Metaphase I: Homologous pairs of c-somes line up on the metaphase plate • Anaphase I: The c-somes (each now having 2 chromatids) of each homologous pair separate and move to the opposite poles of the "cell" • Telophase I: C-somes arrive at the spindle poles • Cytokinesis: Cytoplasm divides producing 2 cells, each having ½ the original number of c-somes Meiosis II Sister Chromatids Separate • Prophase II: Chromosome condense again, the nuclear envelope disappears and the mitotic spindle reforms • Metaphase II: C-somes line along the metaphase plate • Anaphase II: Sister chromatids separate and migrate as individual c-somes to the spindle poles • Telophase II: C-somes arrive at the poles, the spindle breaks down, the nuclear envelope reforms • Cytokinesis: The cytoplasm divides

Differences between prokaryotes and eukaryotes

Eukaryotes: Nucleus: Present Number of chromosomes: More than one Cell Type: Usually multicellular True Membrane bound Nucleus: Present Example: Animals and Plants Genetic Recombination: Meiosis and fusion of gametes Lysosomes and peroxisomes: Present Microtubules: Present Endoplasmic reticulum: Present Mitochondria: Present Cytoskeleton: Present DNA wrapping on proteins: Eukaryotes wrap their DNA around proteins called histones. Ribosomes: larger Vesicles: Present Golgi apparatus: Present Chloroplasts: Present (in plants) Flagella: Microscopic in size; membrane bound; usually arranged as nine doublets surrounding two singlets Permeability of Nuclear Membrane: Selective Plasma membrane with steroid: Yes Cell wall: Only in plant cells and fungi (chemically simpler) Vacuoles: Present Cell size: 10-100um Prokaryotes: Nucleus: Absent Number of chromosomes: One--but not true chromosome: Plasmids Cell Type: Usually unicellular (some cyanobacteria may be multicellular) True Membrane bound Nucleus: Absent Example: Bacteria and Archaea Genetic Recombination: Partial, undirectional transfers DNA Lysosomes and peroxisomes: Absent Microtubules: Absent or rare Endoplasmic reticulum: Absent Mitochondria: Absent Cytoskeleton: May be absent DNA wrapping on proteins: Multiple proteins act together to fold and condense prokaryotic DNA. Folded DNA is then organized into a variety of conformations that are supercoiled and wound around tetramers of the HU protein. Ribosomes: smaller Vesicles: Present Golgi apparatus: Absent Chloroplasts: Absent; chlorophyll scattered in the cytoplasm Flagella: Submicroscopic in size, composed of only one fiber Permeability of Nuclear Membrane: not present Plasma membrane with steroid: Usually no Cell wall: Usually chemically complexed Vacuoles: Present Cell size: 1-10um Simple answer: 1. eukaryotes have a nucleus, while prokaryotes do not 2. eukaryotes have membrane-bound organelles, while prokaryotes do not. The organelles of eukaryotes allow them to exhibit much higher levels of intracellular division of labor than is possible in prokaryotic cells. 3. Eukaryotic cells are, on average, ten times the size of prokaryotic cells. 4. The DNA of eukaryotes is much more complex and therefore much more extnsive than the DNA of prokaryotes. 5. Prokaryotes have a cell wall composed of peptidoglycan, a single large polymer of amino acids and sugar . Many types of eukaryotic cells also have cell walls, but none made of peptidoglycan. 6. The DNA of prokaryotes floats freely around the cell; the DNA of eukaryotes is held within its nucleus and associated with histones (proteins) 7. Eukaryotes undergo mitosis; prokaryotes divide by binary fission (simple cell division)

Characteristics of eukaryotic cells

Eukaryotic cells are larger than prokaryotic cells and have a "true" nucleus, membrane-bound organelles, and rod-shaped chromosomes. The nucleus houses the cell's DNA and directs the synthesis of proteins and ribosomes. Mitochondria are responsible for ATP production; the endoplasmic reticulum modifies proteins and synthesizes lipids; and the golgi apparatus is where the sorting of lipids and proteins takes place. Peroxisomes carry out oxidation reactions that break down fatty acids and amino acids and detoxify poisons; vesicles and vacuoles function in storage and transport. Animal cells have a centrosome and lysosomes while plant cells do not. Plant cells have a cell wall, a large central vacuole, chloroplasts, and other specialized plastids, whereas animal cells do not. Like a prokaryotic cell, a eukaryotic cell has a plasma membrane, cytoplasm, and ribosomes. However, unlike prokaryotic cells, eukaryotic cells have: -a membrane-bound nucleus -numerous membrane-bound organelles (including the endoplasmic reticulum, Golgi apparatus, chloroplasts, and mitochondria) several rod-shaped chromosomes Typically, the nucleus is the most prominent organelle in a cell. Eukaryotic cells have a true nucleus, which means the cell's DNA is surrounded by a membrane. Therefore, the nucleus houses the cell's DNA and directs the synthesis of proteins and ribosomes, the cellular organelles responsible for protein synthesis. The nuclear envelope is a double-membrane structure that constitutes the outermost portion of the nucleus. Both the inner and outer membranes of the nuclear envelope are phospholipid bilayers. The nuclear envelope is punctuated with pores that control the passage of ions, molecules, and RNA between the nucleoplasm and cytoplasm. The nucleoplasm is the semi-solid fluid inside the nucleus where we find the chromatin and the nucleolus. Furthermore, chromosomes are structures within the nucleus that are made up of DNA, the genetic material. In prokaryotes, DNA is organized into a single circular chromosome. In eukaryotes, chromosomes are linear structures. Mitochondria are oval-shaped, double membrane organelles that have their own ribosomes and DNA. These organelles are often called the "energy factories" of a cell because they are responsible for making adenosine triphosphate (ATP), the cell's main energy-carrying molecule, by conducting cellular respiration. The endoplasmic reticulum modifies proteins and synthesizes lipids, while the golgi apparatus is where the sorting, tagging, packaging, and distribution of lipids and proteins takes place. Peroxisomes are small, round organelles enclosed by single membranes; they carry out oxidation reactions that break down fatty acids and amino acids. Peroxisomes also detoxify many poisons that may enter the body. Vesicles and vacuoles are membrane-bound sacs that function in storage and transport. Other than the fact that vacuoles are somewhat larger than vesicles, there is a very subtle distinction between them: the membranes of vesicles can fuse with either the plasma membrane or other membrane systems within the cell. All of these organelles are found in each and every eukaryotic cell. While all eukaryotic cells contain the aforementioned organelles and structures, there are some striking differences between animal and plant cells. Animal cells have a centrosome and lysosomes, whereas plant cells do not. The centrosome is a microtubule-organizing center found near the nuclei of animal cells while lysosomes take care of the cell's digestive process. n addition, plant cells have a cell wall, a large central vacuole, chloroplasts, and other specialized plastids, whereas animal cells do not. The cell wall protects the cell, provides structural support, and gives shape to the cell while the central vacuole plays a key role in regulating the cell's concentration of water in changing environmental conditions. Chloroplasts are the organelles that carry out photosynthesis.

Law of independent assortment?

Genes for different traits are sorted separately from one another so that the inheritance of one trait is not dependent on the inheritance of another.

Who is the father of genetics?

Gregor Mendel (the father of genetics), through his work on pea plants, discovered the fundamental laws of inheritance. He deduced that genes come in pairs and are inherited as distinct units, one from each parent. Mendel tracked the segregation of parental genes and their appearance in the offspring as dominant or recessive traits.

Chloroplast

In eukaryotic cells, the cytoplasm is that part of the cell between the cell membrane and the nuclear envelope. It is the jelly-like substance in a cell that contains the cytosol, organelles, and inclusions, but not including the nucleus. In fact, the cytoplasm and the nucleus make up the protoplasm of a eukaryotic cell. In prokaryotic cells that do not have a well-defined nucleus, the cytoplasm is simply everything enclosed by the cell membrane. It therefore contains the cytosol, and all the other cellular components, including the chromosome in the nucleoid region. The cytoplasm (of both eukaryotes and prokaryotes) is where the functions for cell expansion, growth, metabolism, and replication are carried out.

The sex of an offspring is determined by?

In humans' the sex of the baby is determined by the sperm. The sperm gamete is heterogamatic because approximately half of them contain the X chromosome which will result in a girl and approximately half of them contain the Y chromosome which will result in a boy.

What is mRNA?

Messenger RNA (mRNA) is a large family of RNA molecules that convey genetic information from DNA to the ribosome, where they specify the amino acid sequence of the protein products of gene expression. Following transcription of primary transcript mRNA (known as pre-mRNA) by RNA polymerase, processed, mature mRNA is translated into a polymer of amino acids: a protein. Cellular organisms use mRNA to convey genetic information (using the letters G, U, A, and C to denote the nitrogenous bases guanine, uracil, adenine, and cytosine) that directs synthesis of specific proteins

P, F1, F2 generations?

P generation refers to the parent generation. F1 stands for the first filial generation that was obtained on cross pollinating the parent plants. F2 stands for the second filial generation that is obtained by self pollinating the F1 generation plants. In terms of Mendel's pea plant experiment (the picture): The parent generation is the pure purple plant and the pure white plant, which breed to produce a hybrid purple plant (F1), which has children (F2, the grandchildren of the P generation). The children are either purple or white.

Explain photosynthesis

Photosynthesis allows plants to convert light into food, removes carbon dioxide from the atmosphere and releases oxygen into the atmosphere. Without plants that perform photosynthesis, the oxygen on our planet would be used up and all oxygen breathers would choke on a carbon-dioxide rich atmosphere. Plants absorb red and blue light into the thylakoid membrane of the plant cell, converting it to chemical energy. The chemical energy also is known as adenosine triphosphate, or ATP. Within the chloroplast, carbon dioxide is combined with components from the ATP process to form sugar. Leaves are the solar collectors that begin the photosynthesis process. Leaves are covered with a waxy substance called a cuticle that allows them to retain water. Holes called stoma allow carbon dioxide to enter and oxygen to escape. Xylem cells inside the vein transport water from the roots to the leaves so photosynthesis can take place. Chlorophyll is a complex molecule that absorbs the light rays of the sun. There are two types of chlorophyll molecules, A and B. Type A, found in all organisms that undergo photosynthesis, absorbs violet-blue and reddish orange-red light, whereas type B absorbs green and orange-red light, an adaptation for plants that live below 16 feet of water, where violet-blue and reddish orange-red light has trouble reaching.

RNA polymerase?

RNA polymerase is an enzyme that produces primary transcript RNA. In cells, RNAP is necessary for constructing RNA chains using DNA genes as templates, a process called transcription

Results of mitosis

Results in two daughter cells Results in diploid daughter cells (chromosome number remains the same as parent cell) Daughter cells are genetically identical The end result is that at the end of the cell division, the two daughter cells will have almost exact copies of their parent cell's DNA. Almost every somatic cell type undergoes mitosis. Mitosis: One diploid cell → two diploid cells. Goal is cell division.

What is RNA?

Ribonucleic acid (RNA) is a polymeric molecule essential in various biological roles in coding, decoding, regulation, and expression of genes. RNA and DNA are nucleic acids Like DNA, RNA is assembled as a chain of nucleotides, but unlike DNA it is more often found in nature as a single-strand folded onto itself, rather than a paired double-strand

Spindle fiber?

Spindle fibers form a protein structure that divides the genetic material in a cell. The spindle is necessary to equally divide the chromosomes in a parental cell into two daughter cells during both types of nuclear division: mitosis and meiosis. During mitosis, the spindle fibers are called the mitotic spindle. Meanwhile, during meiosis, the spindle fibers are referred to as the meiotic spindle. At the beginning of nuclear division, two wheel-shaped protein structures called centrioles position themselves at opposite ends of the cell forming cell poles. Long protein fibers called microtubules extend from the centrioles in all possible directions, forming what is called a spindle. Some of the microtubules attach the poles to the chromosomes by connecting to protein complexes called kinetochores. Kinetochores are protein formations that develop on each chromosome around the centromere, which is a region located near the middle of a chromosome. Other microtubules bind to the chromosome arms or extend to the opposite end of the cell. During the cell division phase called metaphase, the microtubules pull the chromosomes back and forth until they align in a plane along the equator of the cell, which is called the equatorial plane. The cell goes through an important checkpoint to ensure that all of the chromosomes are attached to the spindle and ready to be divided before it proceeds with division. Next, during anaphase, the chromosomes are simultaneously separated and pulled by the spindle to opposite poles of the cell.

Base pairing rules for DNA

The purine adenine (A) always pairs with pyrimidine thymine (T). The pyrimidine cytosine (C) always pairs with the purine guanine (G)

What is the purpose of mitosis?

The purpose of mitosis is cell reproduction, regeneration and growth. Mitosis is cell division that occurs in the nucleus of a cell According to Quizlet, growth and repair, allows for direct replication of a cell

What is a cell?

The structural, functional and biological unit of all organisms. A cell is the smallest unit of life that can replicate independently, and cells are often called the "building blocks of life".

Substance that causes cancer is called?

The substance that causes cancer is called a carcinogen. Carcinogens are chemical, physical, biological, or any substances that are agents in causing cancer. If allowed to accumulate in the human body in large amounts or for extended periods of time, there is a higher likelihood that your cells will become damaged, resulting in the growth of cancer cells.

Stages of the cell cycle.

To divide, a cell must complete several important tasks: it must grow, copy its genetic material (DNA), and physically split into two daughter cells. Cells perform these tasks in an organized, predictable series of steps that make up the cell cycle. The cell cycle is a cycle, rather than a linear pathway, because at the end of each go-round, the two daughter cells can start the exact same process over again from the beginning. In eukaryotic cells, or cells with a nucleus, the stages of the cell cycle are divided into two major phases: interphase and the mitotic (M) phase. During interphase, the cell grows and makes a copy of its DNA. During the mitotic (M) phase, the cell separates its DNA into two sets and divides its cytoplasm, forming two new cells. Interphase Let's enter the cell cycle just as a cell forms, by division of its mother cell. What must this newborn cell do next if it wants to go on and divide itself? Preparation for division happens in three steps: G_1. During G_1 , also called the first gap phase, the cell grows physically larger, copies organelles, and makes the molecular building blocks it will need in later steps. S phase. In S phase, the cell synthesizes a complete copy of the DNA in its nucleus. It also duplicates a microtubule-organizing structure called the centrosome. The centrosomes help separate DNA during M phase. G_2 phase. During the second gap phase, or G_2 , the cell grows more, makes proteins and organelles, and begins to reorganize its contents in preparation for mitosis. G_2 phase ends when mitosis begins. The G_1, S, and G_2 phases together are known as interphase. The prefix inter- means between, reflecting that interphase takes place between one mitotic (M) phase and the next.

DNA to RNA to Proteins

To make protein from DNA we first need to take a different step. That is to make RNA from DNA. RNA is important for a lot of different functions but I will only talk about messenger RNA here, which is used to synthesize protein from. RNA (Ribonucleic Acid) is synthesized in the nucleus and is very similar to DNA. The synthesis of RNA also involves the use of bases, but in RNA synthesis no thymine (T) is used but uracil (U) is used instead. The sequence of RNA corresponds to the sequence of DNA from which the RNA is synthesized. The synthesis of RNA from DNA is called transcription (the DNA is transcribed into RNA). In this figure the RNA is being synthesized from the red strand of DNA (which serves as template), this strand of DNA starts with the base T. The RNA strand starts with the only base that can form a base pair with this T, the A. This continues until the complete sequence of RNA is synthesized. Because the red strand serves as template, the sequence of RNA will be identical to the blue strand of DNA, only with the base U instead of the base T. So now we have an RNA strand. From this strand the protein will be synthesized, this is called translation (RNA is translated into protein). A protein is made from amino acids, these form a strand. The translation of RNA to protein is different than the synthesis of RNA from DNA (transcription). When the DNA was transcribed into RNA, one base of DNA corresponded to one base of RNA, this 1 to 1 relation is not used in the translation to protein. During this translation, 1 amino acid is added to the protein strand for every 3 bases in the RNA. So a RNA sequence of 48 bases codes for a protein strand of 16 amino acids

What is tRNA?

Transfer RNA (or abbreviated as tRNA) is small RNA molecule, typically between 70 to 90 nucleotides in length. The primary tRNA function is to deliver amino acids required for the process of protein synthesis. Transfer RNAs are carrying amino acids to the ribosome, where the actual protein synthesis takes place. The molecule is directed by the corresponding codon (a three-nucleotide sequence) in a messenger RNA (mRNA). This defines the role of the tRNA as a required component of protein translation. The process of protein translation defines the production of new proteins according to the genetic information. All transport RNA molecules have similar structures because they all interact with the one and the same sites on the ribosome in a similar way. A transfer RNA is an adaptor molecule composed of RNA, typically 76 to 90 nucleotides in length, that serves as the physical link between the mRNA and the amino acid sequence of proteins. It does this by carrying an amino acid to the protein synthetic machinery of a cell (ribosome) as directed by a three-nucleotide sequence (codon) in a messenger RNA (mRNA). As such, tRNAs are a necessary component of translation, the biological synthesis of new proteins in accordance with the genetic code.

What are the jobs of tRNA?

Transfer RNA (tRNA) is the key to deciphering the code words in mRNA. Each type of amino acid has its own type of tRNA, which binds it and carries it to the growing end of a polypeptide chain if the next code word on mRNA calls for it. The correct tRNA with its attached amino acid is selected at each step because each specific tRNA molecule contains a three-base sequence that can base-pair with its complementary code word in the mRNA. While mRNA contains the "message" as to how to sequence amino acids into a chain, tRNA is the actual translator. Translation of the language of RNA into the language of protein is possible, because there are many forms of tRNA, each representing an amino acid (protein building block) and able to link with an RNA codon. Thus, for instance, the tRNA molecule for the amino acid alanine (A) has an area or binding site for alanine and another binding site for the three RNA nucleotides, the codon, for alanine. tRNA molecules carrying the appropriate amino acid bind to the RNA codon to which they are matched, and the sequence of amino acids is put together.

Translation?

Translation is the process by which a protein is synthesized from the information contained in a molecule of mRNA. In translation, mRNA is decoded by a ribosome, outside the nucleus, to produce a specific amino acid chain, or polypeptide. Translation has three phases; initiation, elongation, and termination. Translation occurs in the cytoplasm of both eukaryotic and prokaryotic cells. Translation, like transcription, occurs throughout interphase. Translation decodes mRNA and uses its information to build a polypeptide, or chain of amino acids. the instructions for building a polypeptide come in groups of three nucleotides called codons. The codons of an mRNA are read in order (from the 5' end to the 3' end) by molecules called transfer RNAs, or tRNAs. Each tRNA has an anticodon, a set of three nucleotides that binds to a matching mRNA codon through base pairing. The other end of the tRNA carries the amino acid that's specified by the codon. tRNAs bind to mRNAs inside of a ribosome and as tRNAs enter slots in the ribosome and bind to codons, their amino acids are linked to the growing polypeptide chain in a chemical reaction. The end result is a polypeptide whose amino acid sequence mirrors the sequence of codons in the mRNA.

What is facilitated diffusion?

Transport of substances across a biological membrane from an area of higher concentration to an area of lower concentration by means of a carrier molecule. Since the substances move along the direction of their concentration gradients, energy is not required. Diffusion refers to the net movement of molecules from higher to lower concentration. Diffusion may be a simple diffusion or facilitated diffusion. A simple diffusion is one in which that occurs unassisted. Facilitated diffusion in contrast is an assisted diffusion in a way that it requires a carrier molecule. For instance, polar molecules diffuse across a cell membrane through carrier molecules in the cell membrane. For example, polar molecules and charged ions dissolved in water cannot diffuse freely across cell membrane due to its hydrophobic lipids. They can only be transported across membranes by proteins forming transmembrane channels. Larger molecules are transported by transmembrane carrier proteins, such as permeases that change their conformation as the molecules are carried through, for example glucose or amino acids

Transcription?

​Transcription is the process by which the information in a strand of DNA is copied into a new molecule of messenger RNA (mRNA) by the enzyme RNA polymerase. The purpose of transcription is to make mRNA that holds the codons that tRNA will translate into amino acids, and eventually a polypeptide. In eukaryotic cells, transcription occurs in the nucleus of the cell. In prokaryotic cells, transcription and translation occur simultaneously in the cytoplasm. Transcription takes place throughout interphase. Interphase is the phase in the life cycle of a cell wherein the cell grows in size, replicates its DNA, and prepares for cell division. Transcription is performed by an enzume called RNA polymerase. RNA polymerase binds to the DNA strand at a promoter, a specific sequence of the gene. The RNA polymerase then winds and unlinks the two strands of DNA, and using one of the DNA strands as a guide, the RNA polymerase matches new nucleotides with their complements on the DNA strand (G with C, A with U). RNA polymerase then binds these new RNA nucleotides together to form mRNA. This process stops when it encounters the stop codon.

Phases of mitosis

• Mitosis (M-phase) which is broken into o Prophase o Metaphase o Anaphase o Telophase o Cytokinesis Mitosis-Prophase • Prophase is when the chromatin becomes tightly coiled Mitosis-Metaphase • Metaphase is when the c-somes align at the metaphase plate. Mitosis-Anaphase • Anaphase occurs when sister chromatids begin to move apart Mitosis-Telophase • Telophase occurs when the 2 daughter nuclei being to form Mitosis-Cytokinesis • Cytokinesis is when a cleavage furrow forms which pinches the cell into two new daughter cells.