Biology Flashcards
Under origin of life,what two approaches help us understand this concept?
Define them each
State and define the types of generations under Philosophy
Origin of life remains a scientific problem which is not yet solved
It is generally agreed that all life today evolved by common descent from a single primitive life form.
It is not known how this early form came about, but scientists think it was a natural process which took place perhaps 3,900 million years ago.
True or false
Religion:
Origin and meaning of life? Two approaches:
1. Religion:
Set of dogmas, usually based on revelation – faith
Incontrovertible truth
E.g. Belief in the supernatural; trust in biblical teachings)
Generally in the form of creation myths – narrative of how the world began and living things inhabit it
Are considered sacred accounts and can be found in nearly all known religious traditions
Are all stories with a plot and characters who are either deities, human-like figures, or animals, who often speak and transform
easily
Philosophy or science :
Confronting the mysteries of the world with questions,
doubts, curiosity, explanatory endeavours
search for natural explanations from observable forces of
nature
Spontaneous generation
formation of living organisms from inanimate matter fleas could arise from dust,
maggots could arise from dead flesh
Mice could arise from a pile of rubbish
Equivocal generation
species arise from unrelated organisms
• Ticks arise from dogs
What is the main hypothesis that supports genetics first and which supports metabolism
Define the hypothesis for both
What did Rudolf Virchow propose in biology? And in which year did he propose what he proposed?
It is not known whether metabolism or genetics came first.
The main hypothesis which supports genetics first is the RNA
World Hypothesis,
self-replicating RNA molecules proliferated before the evolution of DNA and proteins.
The main hypothesis which supports metabolism first is the Protein Interaction World hypothesis.
The’protein interaction world hypothesis of the origins of life assumes that life emerged as a self-reproducing and expanding system of protein interactions.
Rudolf Virchow: Biologist who proposed that all living things are composed of cells, and that all cells arise from pre-existing cells (1858)
Difference between science and religion When were cells first discovered? Who said all plants are made of cells? Who said animals are made up of cells? What is a cell? What are the two types of cellular organisms and state an example each
Religion: Set of often revealed dogmas in which there is no alternative or much leeway in interpretation
Science: Places premium on alternative explanations and readiness to replace one theory with another
Cells were first discovered after examining a thin slice of cock – Robert Hook- 1665. He also contributed to microscopes and did hookes law
Only dead cell walls of plants were observed
All plants are made up of cells – Mathias J. Schleiden
Extended to animals — Theodore Schwann
Cell - basic building block of organisms
Cells can further be broken down to constituent parts.
Constituents parts cannot live and function independently as a living matter.
Unicellular organisms
bacteria, paramecium and amoeba
Multicellular organisms
What are the types of cells? Define them a ns give two examples each
What are the macromolecule components of the plasma membrane?
What about the nucleus?
Which structure in the cell is known as “little organs”?
Which structure in the cell is used for protein synthesis?
Which is used for processing and packaging proteins and lipids?
Which is derived from golgi bodies?
Which structure in green plant cell is used for photosynthesis?
Which structure in a mature green plant cell stores nutrients and toxic waste?
What is the cell wall made up of in plants? What about in fungus?
Between flagella and cilia, which has shorter hair like structures for locomotion?
Which extends from the cell?
Eukaryotic – has nucleus and is bounded by a pair of nuclear envelope
protists, fungi, plants, animals
Prokaryotic cell has no definite nucleus No membrane bound organelle
Nucleoid diffused
bacteria
Akaryotic cells have no nucleus but are merely genetic
information surrounded by a protein coat
include viruses and are sometimes not considered as cells but particles
Cells possess the following basic features:
Cytoplasm: Gel-like substance which is the cell itself
Plasma (Cell) Membrane: Outermost cell surface (proteins, lipids)
Nucleus: Composed primarily of protein and DNA organized into chromosome units (with genes) and enclosed in a membrane
Organelles: A number of microscopic bodies found in cytoplasm; the name means ‘little organs’
Endoplasmic Reticulum (ER): Series of membranes running through cytoplasm, some are studded with ribosomes (rough ER) for protein synthesis
Golgi Body (Apparatus): System of sacs for processing and packaging proteins and lipids
GEMP Tutorial 9
CELL STRUCTURE (2) Lysosome: Derived from Golgi bodies, with enzymes for digestion in the cell Mitochondria: Releases quantities of energy to form ATP; ‘powerhouse’ of the cell Chloroplast: Found in green plant cells for photosynthesis Vacuole: Large, fluid-filled organelle in mature plant cells; stores nutrients and toxic wastes Cell Wall: Found outside plasma membrane in plant (cellulose), fungal (chitin) and bacterial cells; provide support from mechanical pressures Flagella: Long, hair-like organelles extending from the cell, for locomotion Cilia: Shorter hair-like structures for locomotion
State ten differences between animal cells and plant cells
Plant cells have a fixed rectangular shape while animal cells have irregular shape or round shape .
Animal cells have lysosomes but plant cells use their vacuoles for degradation of cellular waste and toxins .
Plant cells have photosynthesis occurring in the mitochondria
Animal cells have smaller and more numerous vacuoles as compared to plant cells vacuoles. Plant cell vacuoles are way bigger. The vacuoles in animal cells are called vesicles. Some vesicles are organelles example, lysosomes,Golgi apparatuses,endosomes,Peroxisomes.
Animal cell membranes give them flexibility since they don’t have cell wall.
Animal cells have centrioles but plant cells don’t
Plant cells have chloroplasts,cell wall, tonoplasts,plasmalemma,glycoxysome and cell wall.
Apart from these, plant cells have everything that animal cells have
A cell has lysosome, mitochondria, Golgi body, smooth
and rough ER. Based on this information, the cell could not be
A. A tapeworm cell
B. A yam cell
C. Yeast cell
D. Escherichia coli cell
E. Plasmodium falciparum cell
You would expect a cell with an extensive Golgi apparatus to
a. make a lot of ATP.
b. secrete a lot of material.
c. move actively.
d. perform photosynthesis.
e. store large quantities of food
Which of the following statements is not correct?
A. A eukaryotic cell contains nucleus that is bounded by nuclear
envelope.
B. A prokaryotic cell has no definite nucleus
C. An akaryotic cells has no nucleus but is merely genetic information surrounded by a protein coat
D. The diffused nuclear material of the eukoryotic cell is the nucleoid.
E. In eukaryotic cells, RNA-synthesis takes place inside the nucleus
whilst protein synthesis occurs in the in cytoplasm.
Find the answers
- Is D. The cell described with lysosomes, mitochondria, Golgi body, smooth and rough endoplasmic reticulum (ER) is characteristic of eukaryotic cells. Among the options provided:
Jhhhhh
- A. A tapeworm cell: Tapeworms are multicellular eukaryotic organisms, so they have cells with organelles like lysosomes, mitochondria, Golgi bodies, and ER.
- B. A yam cell: Yam cells are also eukaryotic and possess these organelles.
- C. Yeast cell: Yeast cells are single-celled eukaryotic organisms that have all these organelles.
- D. Escherichia coli cell: Escherichia coli is a prokaryotic bacterium, which lacks membrane-bound organelles like mitochondria, Golgi bodies, and lysosomes.
- E. Plasmodium falciparum cell: Plasmodium falciparum is a unicellular eukaryotic parasite, and its cells contain organelles such as mitochondria and ER, but may lack some other organelles depending on the stage of its lifecycle.
Therefore, the correct answer based on the presence of lysosomes, mitochondria, Golgi body, smooth and rough ER would be:
D. Escherichia coli cell
Escherichia coli is a prokaryotic cell and does not have membrane-bound organelles like lysosomes, mitochondria, Golgi bodies, smooth ER, or rough ER.
2.Is B
3.D.
Let’s address each question and statement:
-
Question: You would expect a cell with an extensive Golgi apparatus to
-
Answer: b. secrete a lot of material.
- The Golgi apparatus in cells is responsible for modifying, sorting, and packaging proteins and lipids into vesicles for secretion to other parts of the cell or outside the cell. Therefore, a cell with an extensive Golgi apparatus would likely be involved in secreting a lot of material.
-
Answer: b. secrete a lot of material.
-
Statement: Which of the following statements is not correct?
-
Answer: D. The diffused nuclear material of the eukoryotic cell is the nucleoid.
- This statement is incorrect because “nucleoid” is a term used in prokaryotic cells to refer to the region where genetic material (DNA) is located, but it is not surrounded by a membrane-bound nucleus. In contrast, eukaryotic cells have a well-defined nucleus bounded by a nuclear envelope where genetic material is contained within chromosomes.
- A. A eukaryotic cell contains nucleus that is bounded by nuclear envelope.
- This statement is correct. Eukaryotic cells have a nucleus that is surrounded by a double membrane called the nuclear envelope.-
B. A prokaryotic cell has no definite nucleus
- This statement is correct. Prokaryotic cells lack a membrane-bound nucleus; instead, their genetic material is located in a region called the nucleoid.
-
C. An akaryotic cells has no nucleus but is merely genetic information surrounded by a protein coat
- This statement describes a virus, not a cellular organism. Viruses are acellular and consist of genetic material (DNA or RNA) surrounded by a protein coat (capsid).
-
E. In eukaryotic cells, RNA-synthesis takes place inside the nucleus whilst protein synthesis occurs in the cytoplasm.
- This statement is correct. In eukaryotic cells, RNA synthesis (transcription) occurs inside the nucleus, where DNA is transcribed into RNA. The RNA then exits the nucleus and travels to the cytoplasm, where protein synthesis (translation) occurs on ribosomes.the rna in eukaryotes nu, remember we have mrna rrna trna
-
Answer: D. The diffused nuclear material of the eukoryotic cell is the nucleoid.
Therefore, the incorrect statement among the options provided is:
D. The diffused nuclear material of the eukoryotic cell is the nucleoid.
What is a tissue Give two examples each of plant and animal tissues What is an organ What is an organ system Give two examples of each
A tissue is a group of cells that are similar in structure and are bounded by intracellular material to perform a common function. Plants epidermis periderm tissues vascular tissue xylem tissues, phloem tissue parenchyma tissue, sclerenchyma tissue collenchyma Animals Epithelia tissues connective tissues (e.g. blood tissue, cartilage tissue, bone tissue) nerve tissue muscle tissue
Organ
A group of different tissues that perform a common
function are called an organ. The skin of an animal
Tissues :
epithelium, muscle,
nerve,
hair,
blood.
Organ systems
a group of organs that interact to perform a common function
which contributes to the survival of the body.
Digestion system : teeth, stomach, pancreas, intestines etc.
What are carbohydrates
Give two example of carbs that may not follow the normal ratio of H to O
Give two functions of carbs
State the types of carbs
State the types of carbs
Give two examples of disaccharides
Polysaccharides mainly serve as what kind of compounds?
What is the most important monosaccharide ?
What is it’s function?
What monosaccharide is most important as a component of coenzymes
Carbohydrates:
Biological molecules of carbon, hydrogen and
oxygen atoms with ratio of H to O = 2:1
Cm(H2O)n (where m could be different from n)
Some exceptions exist; E.g. deoxyribose, a sugar component of DNA, has the empirical formula
C5H10O4
Source of energy and structural materials for organisms
Storage: e.g., starch and glycogen
Structural: cellulose in plants and chitin in arthropods
Carbohydrates comprising of :
monosaccharides
single molecules- glucose, fructose, galactose
Oligosaccharides —few monosaccharides linked
together. 3-10 monosaccharides
disaccharides – double molecules — bonding of two simple sugars so two
Monosaccharides
- maltose — two glucose ,
- sucrose — glucose + fructose ,
- lactose) —– glucose + galactose
Polysaccharides
Polymeric carbohydrates that include starches, glycogem, cellulose etc
Mainly serve as storage compounds(These are complex carbohydrates known as polysaccharides, formed by linking large numbers of monosaccharides)
Glucose (C6H12O6) is the most important monosaccharide, and basic fuel for living things
The 5-carbon monosaccharide ribose is an important component of coenzymes (e.g., ATP, FAD and NAD) and the backbone of the genetic molecule known as RNA.
The related deoxyribose is a component of DNA.
How is starch,cellulose and glycogen formed
What are proteins
State the functions of proteins
Starch: Composed of hundreds or thousands of glucose units; serves as a storage form of carbohydrates in plants
Glycogen: Important polysaccharide composed of glucose units, but combined differently from those in starch. It is the storage form of glucose in animals
Cellulose: Primarily structural polysaccharide composed of glucose units, but only a few organisms can break it down to release glucose (found in wood, cotton fabric, paper, etc.)
Proteins:
One of the most complex organic compounds, composed of amino
acids (composed of C, H, O and N atoms; also S, P, Fe and Cu)
Differ from one another in their sequence of amino acids which usually results in folding of the protein into a specific three-dimensional structure that determines its activity.
The sequence of amino acid residues in a protein is defined by the sequence of a gene, which is encoded in the genetic code.
Peptide bonds link amino acids,
A linear chain of amino acid residues is called a polypeptide.
Short polypeptides, containing less than about 20-30 amino acis residues, are rarely considered to be proteins and are commonly called
peptides
Building blocks of life
Required by all living things for strengthening and supporting
materials Functions:
Used in production of enzymes, which catalyse biochemical reactions
Structure (hair, horns, keratin, silk, actin and myosin in muscle )
Transport- haemoglobin
Defence-antibodies
What are lipids
Another name for glycerol is ?
Name two common lipids and three functions of lipids
Lipids:
CHEMICAL BASIS OF LIFE ORGANIC COMPOUNDS (3)
Also composed of C, H, O atoms, but higher H:O ratio
Molecules are composed of a glycerol molecule and 1-3 molecules of fatty acids
A fatty acid is a long chain of carbon atoms (4-24) with a carboxyl (- COOH) at the end, while glycerol contains three hydroxyl (-OH) group
Another name is Glycerin
Common lipids include steroids (composition of hormones), waxes and fats
Source of reserve energy supply to the organism
Vitamins A, D, E, and K are fat-soluble, can only be digested,
absorbed, and transported in conjunction with fats.
maintaining healthy skin and hair
Serves as a useful buffer towards a host of diseases
How do cells communicate with the environment
State and define the four ways
MEMBRANE TRANSPORT
Cells communicate with the environment in several ways:
Diffusion: Movement of molecules from region of higher concentration
to one of lower concentration (concentration gradient);
Types are simple diffusion and then facilitated diffusion
Osmosis: Movement of water from region of higher concentration to that of a lower concentration across a semi-permeable membrane
Hypotonic? Isotonic?
Hypertonic?
Facilitated Diffusion: Diffusion assisted by certain proteins in the membrane, from a region of higher concentration to that of a lower concentration. Another name for facilitated diffusion is called passive transport since it doesn’t use energy but requires transport proteins
Active Transport: Movement of a material by a protein across a
membrane from a lower concentration to that of a higher
concentration, with expenditure of energy by the cell (ATP)
Chemical reactions in all living cells operate in the presence of ?
What are they composed of?
What are the characteristics of enzymes?
Chemical reactions in all living cells operate in the presence of enzymes (biological catalysts):
Composed of proteins,
Names end in ‘ase’ (e.g. lipase, protease, etc.)
Characteristics:
1.Specificity:
particular enzyme catalyses only one reaction
2.Lowers activation energy barrier
3.Act on substrates to form end-products:
speed up reactions but remain unchanged at the end
4.Active site of an enzyme interacts with the substrate in ‘lock and key’ fashion (enzyme-substrate complex):
Enzyme-substrate reaction is fast and reversible
Characteristics of an Enzyme : Speed up chemical reactions. They are required in minute amounts. They are highly specific in their action. They are affected by temperature. They are affected by pH. Some catalyze reversible reactions. Some require coenzymes. They are inhibited by inhibitors
Many enzymes work with chemical co-factors or co-enzymes.
Give one example each and state which is organic and which is inorganic
Rate of enzyme catalysed reactions depends on what
co-factors (inorganic- Fe, Mn, Zn) or co-enzymes (organic e.g. biotin) The term “non-protein” is used to differentiate coenzymes from the proteins that make up enzymes themselves. Here’s why organic coenzymes are classified as non-protein:
- Chemical Composition: Coenzymes are small organic molecules that are not composed of amino acids like proteins. Instead, they are typically derived from vitamins or other organic compounds. Their chemical structures are diverse and often include functional groups that are crucial for their role as cofactors in enzyme-catalyzed reactions.
- Role in Enzyme Function: Coenzymes bind to enzymes temporarily, often at the enzyme’s active site or another specific binding site, to assist in the catalytic process. They may donate or accept electrons, atoms, or functional groups during reactions, thereby facilitating the conversion of substrates into products. This interaction is essential for the enzyme to function effectively in metabolic pathways.
- Regeneration and Reuse: Unlike proteins, which are typically synthesized and degraded in cellular processes, coenzymes are not permanently altered or consumed during enzymatic reactions. They can undergo reversible changes or cycles of association and dissociation with enzymes. This characteristic allows coenzymes to participate repeatedly in catalytic reactions, enhancing the efficiency and versatility of enzymatic processes.
- Origin: Many coenzymes are derived from vitamins or vitamin-like compounds. For example, coenzyme A (CoA) is derived from pantothenic acid (vitamin B5), while flavin adenine dinucleotide (FAD) and nicotinamide adenine dinucleotide (NAD+) are derived from riboflavin (vitamin B2) and niacin (vitamin B3), respectively. These organic molecules are synthesized by cells or obtained from the diet and play crucial roles as cofactors in numerous metabolic reactions.
Rate of enzyme-catalysed reactions depends on several factors:
Substrate concentration-increasing the substrate concentration increases the rate of
reaction, to a certain point
Acidity and temperature of environment :Works best at optimum pH and temperature
Presence of other chemicals:
1.Inhibitors –
Harmful… poisons
Useful …. Many drugs
2.Activators
molecules that bind to enzymes and increase their activity
What is mitosis How many phases does it occur in Name them Name the three main functions of mitosis What is meiosis How many phases does it occur? Name each phase and the stages involved in each stage State the main function of meiosis
Mitosis: Cell division which results in two daughter cells with the same number of chromosomes as the parental cell
Occurs in five phases: Prophase, Metaphase, Anaphase, Telophase, Cytokinesis. Mitosis is the process by which cells divide to create two identical daughter cells. Here’s a simple explanation of its phases:
- Interphase: This is the phase before mitosis starts. The cell grows, copies its DNA, and prepares for division.
- Prophase: In prophase, the copied DNA coils up tightly into chromosomes. The nuclear membrane around the nucleus breaks down.
- Metaphase: The chromosomes line up in the middle of the cell. They attach to spindle fibers that stretch from one end of the cell to the other.
- Anaphase: The spindle fibers pull the chromosomes apart. Each half moves to opposite ends of the cell.
- Telophase: The separated chromosomes reach the ends of the cell. New nuclear membranes form around each set of chromosomes, creating two new nuclei.
- Cytokinesis: Finally, the cell pinches in the middle, dividing into two new daughter cells. Each daughter cell gets a copy of the chromosomes and other cell parts.
Three main functions:
Growth of Organisms
Asexual reproduction in simple multicellular organisms
Wound healing or regeneration of body parts
Meiosis: Cell division resulting in halving of chromosome number during gamete formation (human diploid chromosome number of 46 converts into 4 haploid daughter cells each with 23 chromosomes)
Occurs in two main phases:
Meiosis I: Prophase I, Metaphase I, Anaphase I, Telophase I Cytokinesis I
Meiosis II: Prophase II, Metaphase II, Anaphase II, Telophase II, Cytokinesis II
Main function:
Sexual reproduction in complex organisms
In mitosis ,what happens in each stage
Interphase- 46 chromosomes
Prophase- chromosomes double to 92
Prometaphase-nucleus dissolves and microtubules attach to centromeres
Metaphase- chromosomes align at middle of the cell
Anaphase-separated chromosomes pull apart
Telophase- microtubules disappear and cell division occurs
Cytokinesis- two daughter cells formed each with 46 chromosomes
In meiosis what happens in each stage
Interphase 1-46 chromosomes
Prophase 1-chromosomes double to 92
Prometaphase 1-nucleus dissolves and microtubules attach to centromeres
Metaphase 1-chromosomes align at middle of the cell
Anaphase 1-separated chromosomes pull apart
Telophase 1-microtubules disappear and cell division occurs
Interphase 2- two cells formed each with 46 chromosomes
Metaphase 2- microtubules attach to centromeres
Anaphase 2- chromosomes pulled apart to 23
Telophase 2- microtubules disappear and cell division begins
Cytokinesis- 4 cells formed each with 23 chromosomes
Who is the father of genetics and when did he perform his experiments
What plant did he perform it on
Why will we say he was lucky?
Gregor Mendel: Augustinian Monk- Father of Genetics, performed experiments in the 1860s and 1870s
Garden pea or Pisum sativum
Was mendel lucky?
1.
2. 3. 4.
5.
6.
P. sativum were cheap, grow easily and have short life cycles: 3 generations in a year.
The male and female reproductive parts of the f lower were distinguished and large enough for crossing experiments.
Cross pollination rarely took place which means that selfing the plants were easily established.
The seven traits that mendel chose were present on different loci and moreover they showed distinguished phenotypic characteristics.
P. sativum plant produces large number of f lowers and each f lower when crossed would produce pods containing between 2-8 peas
The seven traits that Mendel chose were dominant traits.
co-dominance and incomplete dominanace were discovered
much later, and caused a lot of confusion for a long time. Mendel
was lucky not to come across them
GEMP Tutorial
What is a gene,allele,gene flow,homogous chromosomes,genome,genotype,phenotype,homozygous allele,heterozygous allele,dominant allele,recessive allele,locus
Gene: Fundamental physical unit of heredity (now known to contain DNA in chromosomes)
Allele: Different forms (2 or more) or varieties of a gene occupying the same locus on homologous chromosomes. An allele is a different version of the same gene. For example, consider the gene for flower color in a plant species. If this gene can produce either red flowers or white flowers, then the red flower version of the gene is one allele, and the white flower version is another allele. An allele can be heterozygous or homozygous. Heterozygous example is having a gene for hair color with an allele being black and another being white then homozygous is the same gene for color but the alleles are all black for both. So homologous chromosome,look for the explanation in one of the cards. It’ll make this card too long.
Gene flow: transfer of alleles or genes from one population to another.
Homologous chromosomes: Pair of chromosomes containing the same genetic information
Genome: Set of genes specifying an organism’s traits (100,000 in humans); total genetic information an individual inherits from its parents
Genotype: Genetic composition/constitution of an organism
GEMP Tutorial 34
Phenotype: Outward expression/observable manifestation of specific genotype Homozygous: Two identical alleles present for a particular characteristic (true-breeding) Heterozygous: Two different alleles present for a particular characteristic Dominant Allele: Expressed allele when two are present Recessive Alleles: Overshadowed allele which is only expressed when both are present Locus: Location of a gene on a chromosome
State Mendel’s three laws of genetics
Complete Dominance: When an organism has two different alleles for a trait, one allele dominates. Example-Dominance**: for skin let’s say we have two alleles B and b. If black (B) is dominant over fair (b), individuals with genotype BB or Bb would exhibit black skin color.
- Recessive: If fair (b) is recessive, individuals would need to have the genotype bb to exhibit fair skin color.
Segregation: During gamete formation by a diploid organism, the pair of alleles for a particular trait separate, or segregate, during gamete formation (meiosis) or Mendel’s law of segregation states that during the formation of gametes (sex cells), the two alleles for a gene segregate or separate from each other such that each gamete carries only one allele for each gene.
Independent Assortment: Members of a gene pair separate from one another independently of the members of other gene pairs.
The Law of Independent Assortment applies only when the genes are located on different chromosomes or are far apart on the same chromosome (due to genetic recombination).
So I think the assortment means the genes are randomly assigned to the baby during meiosis and the independent means just because when the sharing was going on, you got big butt gene doesn’t mean you’ll get big boobs too. You getting big boobs gene doesn’t depend on you getting big butt gene.
, “assortment” refers to the random distribution or segregation of alleles (alternative forms of a gene) into gametes during the process of gamete formation (meiosis).
-
Law of Independent Assortment:
- This principle, proposed by Gregor Mendel, states that alleles of different genes segregate (separate) independently of each other during the formation of gametes.
- In other words, the inheritance of one trait (determined by one gene) does not affect the inheritance of another trait (determined by a different gene) when those genes are located on different chromosomes or are far apart on the same chromosome (due to crossing over).
. Sure, let’s explain the Law of Independent Assortment to a 6-year-old in a simple and relatable way:
Imagine you have a box of colorful blocks. Some blocks are red, and some are blue. You also have two baskets to sort these blocks. One basket is for red blocks, and the other is for blue blocks.
Now, when you start putting blocks into the baskets, you close your eyes and pick one block at a time from the box. You don’t look at which color you picked before. You just put each block into its basket based on its color.
The Law of Independent Assortment is a bit like that. It says that when our body makes tiny cells called “egg” or “sperm,” the colors (or traits) they get can be mixed up in a random way. So, if our body has two traits to decide on (like eye color and hair color), they can get mixed up in different ways. This randomness helps make sure that kids can look a bit like their mom or dad or even their grandparents, but also be a little bit different too!
Just like how you randomly sort blocks into baskets, our body sorts traits into new cells in a way that makes each person unique, with a mix of traits from their family.
State the eight principles of genetics and explain four
A mother with type B blood has a type A baby. The husband is refusing paternity. Is he justified?
A couple had a baby and were worried that it did not resemble either of them. The baby’s blood type is O, the father is type A , and the mother is type B. Are they right to conclude that there had been a mix-up at the hospital? Explain.
Incomplete Dominance: In some combinations, dominant alleles do not exist, rather the two alleles blend and both alleles have the opportunity to express themselves (combined expression of two different alleles)(example is in the biology slides) example is have a white gene for a flower and a red gene for another. Instead of having either red or white flowers when they are crossed, they have pink flowers. They don’t have red or white. It’s a blend of the two colors. Neither of the colors are completely dominant over the other. Rather there is a born of the red and white gene.
- Codominance: Where both alleles are completely expressed (e.g.
ABO blood system) In individuals with the genotype IAIB, both A and B alleles are expressed equally, resulting in the blood type AB. This means both A and B antigens are present on the surface of red blood cells. This expression of both alleles in the phenotype without blending is the hallmark of codominance.another example is seeing two different patches of colours on the skin of an animal
3.Linkage: Sometimes, a large number of genes are inherited together, because they are located on the same chromosome. The closer the genes are to each other, the higher the probability that they will be inherited together
- Multiple Alleles: When more than two alleles exist for a particular characteristic
E.g. Human blood groups- A, B, O, where A and B are co- dominant, but both are dominant over O
Thus: Type A (AA and AO); Type B (BB and BO); Type AB (AB) ; Type O (OO) - polygenic inheritance
- pleiotrophy
- epistasis
- sex linkage
