Final

Question 1

explain the benefits of compartmentalization

Answer 1

Different cell organelles perform different functions, many of which require specialized components for specific targets. Compartmentalization creates appropriate microenvironments for these diverse processes, allows damage limitation, minimizes non-specific interactions and consequently increased cellular efficiency.

Question 2

name all of the cell components in a prokaryotic cell

Answer 2

capsule, pilus, cell wall, ribosomes, nucleoid/DNA, cytoplasm, flagellum, plasmid

Question 3

describe the structure and function of the cell components in a prokaryotic cell: capsule

Answer 3

outermost compoent found on some prokaryotic cells. its sticky and can help bacteria interact, provide defense for the cell, and lock in moisture

Question 4

describe the structure and function of the cell components in a prokaryotic cell: plasmid

Answer 4

horizontal gene transfer

Question 5

describe the structure and function of the cell components in a prokaryotic cell: Pilus (pili)

Answer 5

hairlike external feature which plays a role in gene transfer and cojugation (the temporary union of two bacteria or unicellular organisms for the exchange of genetic material).

Question 6

describe the structure and function of the cell components in a prokaryotic cell: cell wall

Answer 6

rigid wall structure that maintain’s cell’s shape. Also important for protection of inner cell components.

Question 7

describe the structure and function of the cell components in a prokaryotic cell: ribosomes

Answer 7

found in the cytoplasm of prokaryotic cells, ribosomes perform translation of mRNA into proteins

Question 8

describe the structure and function of the cell components in a prokaryotic cell: nucleoid/DNA

Answer 8

DNA/Genetic material in prokaryotes is found in a general, irregular shaped mass called the “nuceloid”.

Question 9

describe the structure and function of the cell components in a prokaryotic cell: cytoplasm

Answer 9

Gel-like fluid found inside the cell where all organelles/ components of the cell are found.

Question 10

describe the structure and function of the cell components in a prokaryotic cell: flagellum

Answer 10

Whip-like appendages attatched to the cell that rotates in a circle to allow cells to move

Question 11

name all of the cell components in a eukaryotic cell

Answer 11

plasma membrane, cytoplasm, ribosomes, nucleus (nuclear envelope, chromatin, nucleolus), endoplasmic reticulum (rough and smooth), peroxisome, vacuole, lysosome, cytoskeleton (microtubules, centrosome, intermediate fillaments, microfillaments), golgi apparatus, chloroplasts, mitochondria, plastid.

Question 12

describe the structure and function of the cell components in a eukaryotic cell: plasma membrane

Answer 12

The eukaryotic plasma membrane is a phospholipid bilayer with proteins and cholesterol embedded in it. The plasma membrane controls the passage of organic molecules, ions, water, and oxygen into and out of the cell.

Question 13

describe the structure and function of the cell components in a eukaryotic cell: cytoplasm

Answer 13

The cytoplasm, or cytosol of eukaryotic cells is the gel-like, water-based fluid that occupies the majority of the volume of the cell. Cytoplasm functions as the site of energy production, storage, and the manufacture of cellular components.

Question 14

describe the structure and function of the cell components in a eukaryotic cell: ribosomes

Answer 14

Ribosomes can be found floating within the cytoplasm or attached to the endoplasmic reticulum. Their main function is to convert genetic code into an amino acid sequence and to build protein polymers from amino acid monomers.

Question 15

describe the structure and function of the cell components in a eukaryotic cell: nucleus (nuclear envelope)

Answer 15

membrane enclosing the nucleus. protein lined pores allow material to move in and out

Question 16

describe the structure and function of the cell components in a eukaryotic cell: nucleus (chromatin)

Answer 16

DNA plus assosiated proteins

Question 17

describe the structure and function of the cell components in a eukaryotic cell: nucleus (nucleolus)

Answer 17

condensed region where ribosomes are formed

Question 18

describe the structure and function of the cell components in a eukaryotic cell: endoplasmic reticulum (rough)

Answer 18

assosiated with ribosomes; makes secretory and membrane proteins

Question 19

describe the structure and function of the cell components in a eukaryotic cell: endoplasmic reticulum (smooth)

Answer 19

makes lipids

Question 20

describe the structure and function of the cell components in a eukaryotic cell: peroxisome

Answer 20

metabolizes waste

Question 21

describe the structure and function of the cell components in a eukaryotic cell: vacuole

Answer 21

It is a sac surrounded by a single membrane called a tonoplast. In animal cells, vacuoles are generally small and help sequester waste products. In plant cells, vacuoles help maintain water balance.

Question 22

describe the structure and function of the cell components in a eukaryotic cell: lysosome

Answer 22

digests food

Question 23

describe the structure and function of the cell components in a eukaryotic cell: cytoskeleton (microtubules)

Answer 23

form the mitotic spindle and maintain cell shape

Question 24

describe the structure and function of the cell components in a eukaryotic cell: cytoskeleton (centrosome)

Answer 24

microtubule-organizing center

Question 25

describe the structure and function of the cell components in a eukaryotic cell: cytoskeleton (intermediate fillaments)

Answer 25

fibrous proteins that hold organelles in place

Question 26

describe the structure and function of the cell components in a eukaryotic cell: cytoskeleton (microfilaments)

Answer 26

fibrous proteins; form the cellular cortex

Question 27

describe the structure and function of the cell components in a eukaryotic cell: golgi apparatus

Answer 27

modifies proteins

Question 28

describe the structure and function of the cell components in a eukaryotic cell: chloroplast

Answer 28

site of photosynthesis

Question 29

describe the structure and function of the cell components in a eukaryotic cell: mitochondria

Answer 29

produce energy

Question 30

describe the structure and function of the cell components in a eukaryotic cell: plastid

Answer 30

stores pigments

Question 31

describe the relationship between structure and function

Answer 31

Structure refers to something’s form, makeup or arrangement. Function refers to something’s job, role, task, or responsibility.

Question 32

outline the differences between prokaryotic and eukaryotic cells

Answer 32

In prokayotic cells, the nucleus and membrane bound organelles are absent while they are present in eukaryotic cells. Prokaryotic cells are unicellualar while eukaryotic cells are multicellular. prokaryotic cells are smaller and simpler than eukaryotic cells. Lastly, prokaryotic cells have circular DNA while eukaryotic cells have linear DNA.

Question 33

outline the differences between plant and animal cells

Answer 33

Plant cells have a cell wall, but animals cells do not.
Plant cells have chloroplasts, but animal cells do not. Plant cells usually have one or more large vacuole(s), while animal cells have smaller vacuoles, if any are present. Animal cells come in various sizes (Animal cells are generally smaller than plant cells) and tend to have round or irregular shapes. Plant cells are more similar in size and are typically rectangular or cube shaped. Animals cells store energy in the form of the complex carbohydrate glycogen. Plant cells store energy as starch.

Question 34

explain how monomers combine to form polymers by dehydration reactions and how the process is reversed by hydrolysis reactions

Answer 34

The monomers combine with each other using covalent bonds to form larger molecules known as polymers. In doing so, monomers release water molecules as byproducts. The process of hydrolysis is the reverse reaction, meaning that the water is recombined with the two hydroxyl groups and the disaccharide reverts to being monosaccharides.

Question 35

explain why phospholipids form a bilayer when dissolved in water

Answer 35

In phospholipids, the two fatty acids (heads) are hydrophobic, or insoluble in water. But the phosphate (tails) group is hydrophilic, or soluble in water. When phospholipids are mixed with water, they spontaneously rearrange themselves to form the lowest free-energy configuration. This means that the hydrophobic regions find ways to remove themselves from water, while the hydrophilic regions interact with water. The resulting structure is called a lipid bilayer.

Question 36

describe the fluid-mosaic model of membrane structure

Answer 36

• The main fabric of the membrane is composed of amphiphilic or dual-loving, phospholipid molecules.
• Integral proteins, the second major component of plasma membranes, are integrated completely into the membrane structure with their hydrophobic membrane-spanning regions interacting with the hydrophobic region of the phospholipid bilayer.
• Carbohydrates, the third major component of plasma membranes, are always found on the exterior surface of cells where they are bound either to proteins (forming glycoproteins ) or to lipids (forming glycolipids).

Question 37

define membrane fluidity as well as the factors that influence it

Answer 37

Fluidity is a term used to describe the ease of movement of molecules in the membrane.

FACTOR #1: THE LENGTH OF THE FATTY ACID TAIL: the longer the phospholipid tails, the more interactions between the tails are possible and the less fluid the membrane will be.

FACTOR #2: TEMPERATURE: As temperature increases, so does phospholipid bilayer fluidity.

FACTOR #3: CHOLESTEROL CONTENT OF THE BILAYER: At low temperatures, phospholipids tend to cluster together, but steroids in the phospholipid bilayer fill in between the phospholipids, disrupting their intermolecular interactions and increasing fluidity. The opposite for high tempatures.

FACTOR #4: THE DEGREE OF SATURATION OF FATTY ACIDS TAILS: Unsaturated fatty acids have more distance between the tails and thus fewer intermolecular interactions and more membrane fluidity.

Question 38

define membrane permeability as well as the factors that influence it

Answer 38

The permeability of a membrane is the rate of passive diffusion of molecules through the membrane. The permeability of a membrane is affected by temperature, the types of solutes present and the level of cell hydration. Increasing temperature makes the membrane more unstable and very fluid. Decreasing the temperature will slow the membrane. On the type of solutes, we have large molecules that can never pass across the membrane, others that can pass across but with the aid of protein channels, and those that transfer through membrane through diffusion. The lower hydration levels reduce the ability to permit molecules. The lower the level of cell hydration, the lower the permeability.

Question 39

explain why some molecules are more permeable than others are

Answer 39

Small molecules that are nonpolar (have no charge) can cross the membrane easily through diffusion, but ions (charged molecules) and larger molecules typically cannot.

Question 40

explain the process of osmosis and how it affects cell structure

Answer 40

The process of osmosis moves water molecules across the semipermeable membrane when there is a concentration gradient such that there are different concentrations of solute on each side of the biological membrane. This can affect cell tonicity and cause a cell to be hypotonic, isotonic, or hypertonic.

Question 41

to predict the direction of water movement based on differences in solute concentrations using the terms hypertonic, hypotonic, and isotonic

Answer 41

Our body fluids contain salts dissolved and suspended in water. These fluids are present in both intracellular and extracellular fluids, separated by a semi-permeable membrane. According to the concentration of the solute, the water move across the membrane (osmosis), this ability of osmosis to draw water to build up certain pressure is called osmotic pressure. So, water always moves to maintain uniform pressure in and outside of the cell, hence all the intracellular and extracellular fluids are isotonic.

The fluids having lower osmotic pressure than the body fluids are known as hypotonic solutions. If cells are placed in hypotonic solution, they draw water from the solution and swell.

The fluids having more osmotic pressure than the body fluids are known as hypertonic solutions. The cells placed in hypertonic solutions shrink as they lose water into the surrounding hypertonic solution.

Question 42

describe and draw the basic structure of an amino acid

Answer 42

Each amino acid has the same fundamental structure , which consists of a central carbon atom, also known as the alpha (α) carbon, bonded to an amino group (NH2), a carboxyl group (COOH), and to a hydrogen atom. Both the amino group and the carboxyl group are ionized under physiological conditions, and so have the structures -NH3+ and -COO–, respectively. Every amino acid also has another atom or group of atoms bonded to the central atom known as the R group. This R group, or side chain, gives each amino acid proteins specific characteristics, including size, polarity, and pH.

Question 43

what are the four levels of protein structure and how are they stabalized

Answer 43

The primary structure is held together by covalent peptide bonds.

Secondary structure is stabilized by particularly hydrogen bonding.

The tertiary structure is generally stabilized by outside polar hydrophilic hydrogen and ionic bond interactions, and internal hydrophobic interactions between nonpolar amino acid side chains.

The quaternary structure is stabilized by the same non-covalent interactions and disulfide bonds as the tertiary structure.

Question 44

give examples of the general functions that are carried out by different proteins

Answer 44

Antibody: Antibodies bind to specific foreign particles, such as viruses and bacteria, to help protect the body. Ex: Immunoglobulin G (IgG)’

Enzyme: Enzymes carry out almost all of the thousands of chemical reactions that take place in cells. They also assist with the formation of new molecules by reading the genetic information stored in DNA. Ex: Phenylalanine hydroxylase

Messenger: Messenger proteins, such as some types of hormones, transmit signals to coordinate biological processes between different cells, tissues, and organs. Ex: Growth hormone

Structural component: These proteins provide structure and support for cells. On a larger scale, they also allow the body to move. Ex: Actin

Transport/storage: These proteins bind and carry atoms and small molecules within cells and throughout the body. Ex: Ferritin

Question 45

outline the general steps of the central dogma and relate them to gene expression

Answer 45

Information from a gene is used to build a functional product in a process called gene expression. A gene that encodes a polypeptide is expressed in two steps. In this process, information flows from DNA → RNA → protein, a directional relationship known as the central dogma of molecular biology. (DNA replication, transcription, translation).

Question 46

explain the difference between the coding and non-coding strand as well as their role as template and non-template strand during transcription

Answer 46

A coding strand is a strand that contains the codons. The non-coding strand is the strand that contains the anti-codons. The template strand is called the noncoding strand. The nontemplate strand is referred to as the coding strand because its sequence will be the same as that of the new RNA molecule.

Question 47

describe the three modifications in RNA processing that take place in eukaryotic cells

Answer 47

These include splicing: the process by which introns, the noncoding regions of genes, are excised out of the primary messenger RNA transcript, and the exons (i.e., coding regions) are joined together to generate mature messenger RNA. Capping: the cap is added to the first nucleotide’s 5’ hydroxyl group of the growing mRNA strand while transcription is still occurring. Addition of a poly-A tail: a long chain of adenine nucleotides that is added to a messenger RNA (mRNA) molecule during RNA processing to increase the stability of the molecule.

Question 48

provide examples of the three characteristics of the genetic code as well as explain what makes this code universal

Answer 48

The genetic code is universal.
The genetic code is unambiguous.
The genetic code is redundant.

DNA is considered a universal genetic code because every known living organism has genes made of DNA

Question 49

describe the three stages of translation

Answer 49

During initiation, the small ribosomal subunit binds to the start of the mRNA sequence. Then a transfer RNA (tRNA) molecule carrying the amino acid methionine binds to what is called the start codon of the mRNA sequence. The start codon in all mRNA molecules has the sequence AUG and codes for methionine. Next, the large ribosomal subunit binds to form the complete initiation complex. During the elongation stage, the ribosome continues to translate each codon in turn. Each corresponding amino acid is added to the growing chain and linked via a bond called a peptide bond. Elongation continues until all of the codons are read. Lastly, termination occurs when the ribosome reaches a stop codon (UAA, UAG, and UGA). Since there are no tRNA molecules that can recognize these codons, the ribosome recognizes that translation is complete. The new protein is then released, and the translation complex comes apart.

Question 50

distinguish between exergonic and endergonic reactions

Answer 50

The exergonic reaction is a type of reaction in which free energy is released while Endergonic reactions are the type of reaction in which free energy is absorbed. Exergonic reactions do not require energy to begin while Endothermic reactions always require energy to begin. All the exothermic reactions are exergonic. All endothermic reactions are endothermic. In Exergonic reactions, Gibbs free energy is negative. However in Endergonic reacitons, Gibbs free energy is positive. Lastly, exergonic reactions are a downhill reaction while endergonic reactions are an uphill reaction.

Question 51

describe the process of energetic coupling

Answer 51

Energy coupling occurs when the energy produced by one reaction or system is used to drive another reaction or system.

Question 52

explain how cells use the energy released by ATP hydrolysis to drive endergonic reactions

Answer 52

Cells use ATP to perform work by coupling ATP hydrolysis’ exergonic reaction with endergonic reactions. ATP donates its phosphate group to another molecule via phosphorylation. The phosphorylated molecule is at a higher-energy state and is less stable than its unphosphorylated form, and this added energy from phosphate allows the molecule to undergo its endergonic reaction.

Question 53

explain how enzymes increase the rates of chemical reactions by lowering the activation energy

Answer 53

Enzymes are biological catalysts. Catalysts lower the activation energy for reactions. The lower the activation energy for a reaction, the faster the rate. Thus enzymes speed up reactions by lowering activation energy.

Question 54

explain what happens when one of the enzymes in a metabolic pathway does not work properly

Answer 54

If one step is blocked because an enzyme is unable to function, product E may not be formed; if E is necessary for some vital function, disease results. Many inherited diseases and conditions of humans result from a deficiency of one enzyme.

Question 55

define REDOX reaction as well as the role of electron donor and acceptor have in them

Answer 55

oxidation-reduction (redox) reactions are where electrons are passed from an electron donor to an electron acceptor. The oxidation of a molecule refers to the loss of its electrons, while the reduction of a molecule refers to its gain of electrons. A molecule being oxidized is acting as an electron donor, while the molecule being reduced is acting as an electron acceptor.

Question 56

describe the process of glycolysis in terms of which molecules are put in and its products

Answer 56

In glycolysis, glucose is split into two molecules of pyruvate. This process yields two ATP molecules, two pyruvate molecules, molecules of NADH, and two molecules of water.

Question 57

describe the process of breakdown of pyruvate in terms of which molecules are put in and its products

Answer 57

a carboxyl group is removed from pryuvate, releasing carbon dioxide. NAD+ is reduced to NADH. An acetyl group is transfered to coenzyme A, resulting in acetyl CoA

Question 58

describe the process of the citric acid cycle in terms of which molecules are put in and its products

Answer 58

takes in acetyl CoA and produces carbon dioxide, NADH, FADH2, and ATP or GTP.

Question 59

outline how the electron transport chain produces an H+ electrochemical gradient

Answer 59

In an electron transport system, energy from electron transfer during oxidation-reduction reactions enables certain carriers to transport protons (H+) across a membrane. As the H+ concentration increases on one side of the membrane, an electrochemical gradient called proton motive force develops

Question 60

explain how during oxidative phosphorylation ATP synthase utilizes the H+ electrochemical gradient to produce ATP

Answer 60

Instead of being turned by water, it’s turned by the flow of H +start superscript, plus, end superscript ions moving down their electrochemical gradient. As ATP synthase turns, it catalyzes the addition of a phosphate to ADP, capturing energy from the proton gradient as ATP.

Question 61

explain how fermentation takes place in muscle cells

Answer 61

Muscle cells have the ability to produce a small amount of ATP through glycolysis in the absence of oxygen. The muscle cells convert glucose to pyruvic acid. An enzyme in the muscle cells then converts the pyruvic acid to lactic acid. As in the yeast, this reaction frees up the NAD while providing the cells with two ATP molecules from glycolysis.

Question 62

categorize organisms as autotroph, photoautotroph, or heterotroph

Answer 62

Autotroph: An organism that is able to form nutritional organic substances from simple inorganic substances such as carbon dioxide. (Plants, algae, and some bacteria)

Photoautotroph: any organism that derives its energy for food synthesis from light and is capable of using carbon dioxide as its principal source of carbon. (Higher plants (maize plant, trees, grass etc), Euglena, Algae (Green algae etc), Bacteria (e.g. Cyanobacteria)).

Heterotroph: Heterotrophs cannot produce organic compounds from inorganic sources and therefore rely on consuming other organisms in the food chain. (Herbivores, omnivores, and carnivores)

Question 63

describe the materials and products of the two stages of photosynthesis (the light reactions and the Calvin Cycle) as well as the location of chloroplast where they happen

Answer 63

During the first stage, water is used and oxygen is produced. In the second and final stage, carbon dioxide is used, and glucose is produced. The chloroplast is involved in both stages of photosynthesis. Unlike the light reactions, which take place in the thylakoid dics (membrane), the reactions of the Calvin cycle take place in the stroma (the inner space of chloroplasts).

Question 64

compare the structures of a DNA nucleotide and an RNA nucleotide and know how to differentiate them

Answer 64

There are two differences that distinguish DNA from RNA: (a) RNA contains the sugar ribose, while DNA contains the slightly different sugar deoxyribose (a type of ribose that lacks one oxygen atom), and (b) RNA has the nucleobase uracil while DNA contains thymine.

Question 65

interpret Chargaff’s rules and explain the rules of complementary base pairing

Answer 65

Chargaff’s rule, also known as the complementary base pairing rule, states that DNA base pairs are always adenine with thymine (A-T) and cytosine with guanine (C-G). A purine always pairs with a pyrimidine and vice versa. However, A doesn’t pair with C, despite that being a purine and a pyrimidine.

Question 66

describe the functions of helicase

Answer 66

Helicases are enzymes that bind and may even remodel nucleic acid or nucleic acid protein complexes. DNA helicases are essential during DNA replication because they separate double-stranded DNA into single strands allowing each strand to be copied.

Question 67

describe the functions of topoisomerase

Answer 67

Topoisomerase is a valuable enzyme for untangling supercoils and making space for new DNA strands to be created. Topoisomerase can both cleave DNA at a desired replication site and also ligate the DNA once the process is complete.

Question 68

describe the functions of single-strand binding protein

Answer 68

Single-stranded DNA-binding protein (SSB) binds to single-stranded regions of DNA. During DNA replication, SSB molecules bind to the newly separated individual DNA strands, keeping the strands separated by holding them in place so that each strand can serve as a template for new DNA synthesis.

Question 69

describe the functions of primase

Answer 69

Primase catalyzes the synthesis of a short RNA (or DNA in some organisms) segment called a primer complementary to a ssDNA (single-stranded DNA) template.

Question 70

describe the functions of ligase

Answer 70

ligase is an enzyme that can catalyze the joining of two large molecules by forming a new chemical bond.

Question 71

describe the functions of DNA polymerases III and I

Answer 71

The main function of the third polymerase, Pol III, is duplication of the chromosomal DNA. DNA polymerase I functions to fill DNA gaps that arise during DNA replication, repair, and recombination.

Question 72

outline the key differences between the synthesis of the leading and lagging strands

Answer 72

• A leading strand is the strand which is synthesized in the 5’-3’direction while a lagging strand is the strand which is synthesized in the 3’-5’ direction.
• The leading strand is synthesized continuously while a lagging strand is synthesized in fragments which are called Okazaki fragments.
• Leading strand synthesis does not require an RNA primer while a lagging strand synthesis requires RNA primase.

Question 73

define what a chromosome is, explain the relationships between DNA, genes, chromosomes, sister chromatids, and centromeres

Answer 73

A chromosome is a structure found inside the nucleus of a cell. Before a cell can divide, it must first replicate its DNA so that each of the two daughter cells will receive a complete copy of the DNA. The two identical chromosomes that result from DNA replication are referred to as sister chromatids. Sister chromatids are held together by proteins at a region of the chromosome called the centromere.

(Genes are fragments of DNA that would determine your biological traits.)

Question 74

explain what the “n number” of a cell is as well as explain the difference between a haploid and a diploid cell

Answer 74

The n number of a cell is the sets of chromosomes.

Diploid refers to the number of complete chromosome sets present in each cell of an organism: diploid cells contain two complete sets. Haploid organisms, on the other hand, only contain one complete chromosome set.

Question 75

list the phases of the eukaryotic cell cycle and explain the major events that occur in each one

Answer 75

Interphase: During interphase, the cell copies its DNA in preparation for mitosis. This phase is divided into 3 shorter phases : G1, S and G2.

G1 : During this phase, the cell grows in preparation for DNA replication. Cellular components such as organelles and centrosomes are replicated.

S : S is the phase where the DNA packed into chromosomes is duplicated. Replication of DNA by a certain enzyme is essential as it allows each cell created by the division to have the exact same genetic make-up. At the end of this phase, the cell contains twice its genetic material.

G2 : During this phase, a certain enzyme checks and corrects any error in the duplication of the genetic material.

Mitosis: During mitosis, the cell is split into two independent and identical cells. Mitosis is divided into 4 shorter phases : prophase, metaphase, anaphase and telophase.

Prophase : The chromosomes start to condense and the nucleolus disappears. The nuclear envelope breaks down.

Metaphase : Chromosomes align at the metaphase plate which is the centre of the cell.

Anaphase : Chromatids of each chromosome are separated and start migrating towards opposite poles of the cell.

Telophase : Nuclear membranes reappears, one for each set of chromosomes. Chromosomes decondense.

Cytokinesis: Cytokinesis is the division of the cytoplasm to form two cells. In the case of an animal cell, the cell is pinched in two, it is called cleavage furrow. In the case of plant cells, the cell plate forms down the middle of the cell, splitting it into two daughter cells.

Question 76

explain the difference between homologous chromosomes and sister chromatids

Answer 76

Homologous Chromosomes: Homologous chromosomes are a couple of one maternal and one paternal chromosome, paired up during fertilization in a diploid cell. Sister Chromatids: The two copies of one chromosome, linked together in the centromere are called sister chromatids.

Question 77

describe the structure and function of the mitotic spindle

Answer 77

The mitotic spindle is a proteinaceous structure formed from the microtubules that arise from centrioles. The major function of the mitotic spindle is the separation of duplicated chromosomes in the anaphase stage of mitosis.

Question 78

explain the role of mitosis and meiosis processes in the life cycle of a vertebrate animal as well as the time of fertilization and formation of the zygote

Answer 78

The function of mitosis is to replicate a cell creating two genetically identical diploid cells. This is useful in growth and repair, and asexual reproduction. The function of meiosis is to combine maternal and paternal genes (haploid gametes) to produce a diploid zygote with the right number of chromosomes. The zygote enters the uterus in 3 to 5 days. In the uterus, the cells continue to divide, becoming a hollow ball of cells called a blastocyst. The blastocyst implants in the wall of the uterus about 6 days after fertilization.

Question 79

explain independent assortment and calculate the number of possible chromosomal combinations in gametes

Answer 79

The Principle of Independent Assortment describes how different genes independently separate from one another when reproductive cells develop. The number of chromosome combinations is 4.

Question 80

explain how non-disjunction leads to the occurrence of aneuploidy and provide an example in humans

Answer 80

One cause of aneuploidy is nondisjunction during meiosis, resulting in either extra chromosomes (e.g., trisomy, tetrasomy) or one less chromosome (i.e., monosomy). Trisomy is the most common aneuploidy. In trisomy, there is an extra chromosome. A common trisomy is Down syndrome.

Question 81

distinguish between trait, gene and allele.

Answer 81

A gene is a portion of DNA that determines a certain trait. An allele is a specific form of a gene. Genes are responsible for the expression of traits. Alleles are responsible for the variations in which a given trait can be expressed.

Question 82

genotype vs phenotype

Answer 82

The genotype is a set of genes in the DNA which are responsible for the unique trait or characteristics. Whereas the phenotype is the physical appearance or characteristic of the organism.

Question 83

define Mendel’s law of segregation and law of independent assortment

Answer 83

Mendel’s Law of Segregation states individuals possess two alleles and a parent passes only one allele to his/her offspring. Mendel’s Law of Independent Assortment states the inheritance of one pair of factors ( genes ) is independent of the inheritance of the other pair.

Question 84

explain why X-linked recessive traits are more likely to occur in males

Answer 84

A male with a mutation in a gene on the X chromosome is typically affected with the condition. Because females have two copies of the X chromosome and males have only one X chromosome, X-linked recessive diseases are more common among males than females.