Part 6 Flashcards
Dominant Phenotype
the phenotype that is presented 100% of the time
Recessive Phenotype
traits that are masked if dominant alleles are also present
Phenotypes
are traits
Y or y
Homozygous
Organisms that have a pair of identical alleles for a particular gene
a pea plant that is YY is homozygous dominant for seed color
One that is yy is homozygous recessive for seed color
Heterozygous
if the organism has different alleles for a gene
one that is Yy is heterozygous
Genotypes
are the three allele pairs so YY, Yy, yy
Punnett Square
a handle mathematical tool for predicting the phenotypes of offspring based on the gene types of the parents.
Punnet squares and chromosomes
Organisms like humans are diploid, meaning that their cells contain two sets of chromosomes.
We call the diploid state 2n, where n represents one set of chromosomes
Cell division in a diploid organism is preceded by replication of the genome. the duplicate chromosomes are organized and then separated from one another in a cell division process called mitosis so a cell that is 2n yields two new cells and each is 2n.
Meiosis
The division process that produces gametes.
Gamete formation requires two rounds of cell division, including two rounds of nuclear division but with only one round of DNA replication and two pairs of chromosomes are divided into pairs of chromosomes, which are separated into individual chromosomes.
The results of this is haploid cells containing only a single chromosome set. SO for each special diploid cell (2n) that undergoes meiosis, four haploid gametes are formed (n + n + n + n)
Monohybrid cross
it looks how a single trait is inherited when two heterozygotes are mated
Dihybrid cross
a cross between parents heterozygous at two specific genes
reveal the process of independent assortment
the second law of inheritance is the law of independent assortment.
Non-Mendelian Inheritance
incomplete dominance, Codominance, Epistasis
traits that do not follow patterns of inheritance and expression
incomplete Dominance
Incomplete dominance is apparent because the heterozygote exhibits a phenotype that is intermediate between the two homozygous parents.
so if C is chestnut color and CR is cream if the gene type is C/CR the color is diluted by the cream making it a totally different color. This is incomplete dominance
Codominance
sometimes two alleles can exhibit their phenotypes equally in the heterozygote
Blood type is determined by a gene that has three alleles i^A, i^B, and i
the children of parents who are i^A/i^A and I^B/I^B will be I^A/I^B
the i^A/i^A parent is type A, because it exhibits a particular sugar on the surface of its red blood cell and same with i^B/i^B it displays a different sugar. Their children are both type AB and exhibit both sugars.
people who have type O blood have neither sugar on their red blood cells and the genotype of people with type O blood is i/i
Epistasis
Inheritance results from interactions among two or more genes
is a type of gene interaction in which the phenotype of a trait is the result of one gene’s alleles affecting the alleles of another independently inherited gene.
Black coat color dominant over chocolate so B/B or B/b and chocolate labs are b/b but there is a second gene that affects the pigment of the animals coat.
the deposition gene has two alleles E and e and E is dominant. Any lab that is homozygous recessive e/e for the deposition gene will be a yellow lab, regardless of the gene type B gene. So the E gene is epistatic on the B gene.
its only yellow when the deposition gene is homozygous recessive. so e/e doesnt matter what B is
Atom
Is the fundamental constituent of matter that retains the properties of an element
Atoms can lose, gain, or share electrons to make a variety of chemical bonds of varying strengths and properties.
atoms undergo chemical reactions by gaining or losing electrons to achieve stability.
an atoms properties can be inferred by its position on the periodic table, which relates to the number of valence electrons in its outermost shell
Elements and Atoms
the atoms of each element have distinct configurations that give the element unique chemical and physical properties, but all atoms are composed of the same three fundamental particles: protons, neutrons, and electrons
Where an element is represented on the periodic table is indicative of its number of protons, valence shell configuration, and chemical and physical properties
Elements
the elements that make up the majority of living organism are carbon, hydrogen, oxygen, and nitrogen
Every element has its own characteristic identity that determines how it will interact with other elements and these chemical properties depend on the structure of an elements smallest unit, the atom.
Atom
Contains three primary types of components: electrons, protons, and neutrons
Electrons
are negatively charged subatomic particles that move around the center of the atom in regions known as orbitals
each orbital can hold two electrons and orbitals group together to make up a shell.
Orbitals and Shells
within shells, orbitals are arranged into subshells labeled s,p,d and F where s subshells are closest to the nucleus.
the number of orbitals and shells that an element’s atom contains depends on the number of electrons within the atom
Valence electrons
Electrons in an atoms’s outermost shell are valence electrons and include the electrons involved in bonding between atoms.
Neutrons
in the center of the atom, the atomic nucleus are subatomic particles without a charge
Protons
Subatomic particles that are positive and are also located in an atom’s nucleus
Periodic Table
a chart that organizes elements by their chemical properties
Atomic Mass
is the sum of the mass of protons and neutrons in one atom of an element
the decimal component of the atomic mass is the result of averaging atomic versions of an element that differ in their number of neutrons
Atomic Number
is the number of protons in one atom of an element
it is consistent to every atom of a particular element
arranges elements by increasing atomic number, starting at the upper left hand corner
Period
the rows of the periodic table
each box contains information about an element that has one more proton per atom
numbered from top to bottom, starting with the number one and indicate the shell number that is the valence shell
subshells etc
period numbers are also the same as the number of subshells within each shell.
Shell number 2 is the valence shell of an element in the second period, and that shell contains one subshells of s orbitals and one one subshells made up of three p orbitals.
Elements in period 3 have three subshells, subshells s, subshells P, and subshells D
the number of electrons in an atom of a period 3 element determines the number of orbitals occupied within each subshells
Columns of the periodic table
Columns of the periodic table correspond to configurations of elements’ electrons in their valence shell.
Each column group contains elements that have similar chemical and physical properties
Ways to Label groups
Two ways to label groups
the traditional way labels the groups with Roman numbers and the letter “A” or “B”
the number of valence electrons for an element in an “A” group is the same as its roman numberal
Isotopes
Versions of the same elements with different numbers of neutrons are isotopes of each other
For example, carbon-12 has six protons and six neutrons, while carbon-14 has six protons and eight neutrons
could also have different electrons
Atom in neutral state
In an atom’s neutral state, the number of protons and electrons are equal so the whole number in an elements box on the periodic table also indicates the number of electrons in an uncharged atom of that element.
Ion
When the number of protons and electrons are not equal in an atom, the atom has a charge and is considered to be an ion
Because protons dont leave an atoms nucleus the only way that an atom can develop one or more full charges is by either gaining or losing electrons
Cation
If a neutral atom loses one or more electrons, the positive charge of its protons shows through
as a result the charge of the ion is positively charged and called a cation
Anion
If a neutral atom gains one or more electrons, it becomes a negatively charged ion called an anion
Ionic Bond
Results from the attraction between two oppositely charged ions when one atom is strong enough to “steal” one, two, or three electrons from the other atom
Covalent Bond
is the result of two or more atoms “sharing” electrons so that each atom involved becomes more stable
The electrons involved are not transferred from one atom to the other rather the electrons circulate in the orbitals of both atoms, where they are shared.
typical formed between “p” orbitals
Ionic and Covalent Bond
The number of electrons involved is determined by how many valence electrons exist in the participating atoms
Atoms stable state
At their most stable state when their valence shells are filled
with the exception of hydrogen and helium, an atoms valence shell is full when it contains eight electrons
elements in the group of noble gases already have full valence shells so their atoms do not form bonds
Element bonding
Through bonding atoms either gain access to electrons that bring them close to valence shell fulness, or as ions, become drawn to a more stable oppositely charged ion
Ionic Bond Valence Shell
in an ionic bond, the atom that has a valence shell closer to being filled has enough attractive force to transfer at lease one electron to itself from the weaker atom
by one atom gaining electron
Covalent Bonding
When the number of valence shell electrons of atoms are same or similar, covalent bonding occurs instead of ionic bonding.
Example of Covalent Bonds
an example is the formation of O2 from two oxygen atoms
Up to six electrons can be shared between two atoms
because each pair of shared electrons forms one bond, it is possible for a single, double, or triple covalent bond to form between two atoms.
