exam 2 Flashcards
what is dominant
an allele that is expressed in n organisms phenotype and that simultaneously masks the effects of another allele, if another one is present
what is recessive
an allele that is expressed in an organisms phenotype if two copies are present but is masked if the dominant allele is present
what is the phenotype of an individual?
physical expression of the genotype; may be influenced by environment
example of phenotype
actual physical appearance (tall,short)
example of genotype
pair of alleles such as TT, Tt, tt
what is genotype
genetic make up of an organism; the combination of alleles for a given gene
what are chromosomes
the strand of dna found in the nucleus of eukaryotes that contain hundreds or thousands of genes
what type of observations did mendel make?
discrete physical unit was responsible for each characteristic, this unit passed from parent to offspring, and in this way the characteristic was inherited.
garden peas traits did not blend. ex: plants and their offspring were either tall or short. overtime shortplants diminished
what is allele
one or more alternative forms of a gene
what is mendelian inheritance
basic principles associated with the transmission of genetic material, forming the basis of genetics, including the law of segregation and the law of independent assortment
what is a trait?
characteristics ( tall short)
law of segregation
- monohybrid cross
- each individual has two factors for each trait
- the factors segregate during the formation of the gametes
- each gamete contains only one factor from each pair of factors
- fertilization gives each new individual two factors for each trait
law of independent assortment
- each pair of factors segregates (assorts) independently of the other pairs
- all possible combinations of factors can occur in the gametes
concept of blending
idea that parents of contrasting appearance always produced offspring of intermediate appearance
what are the Two laws that describe the behavior of genes as they are passed from one generation to the next
law of segregation and law of independent assortment
when mendel crossed a true breeding violet flowered and a true breeding white flowered plant, the offspring were
all violet
when mendel crossed a true breeding tall with a true breeding dwarf plant, all of the f1 generation were tall. therefore we may conclude that the allele for dwarfism in the pea plant is
recessive
cytogenetics ( the study of the mechanisms of heredity in the cell ) shows that mendel’s principle of segregation
is based on the separation of chromosomes during meiosis
two nontastsers for ptc will have among their offspring
nontastsers only
the blending theory is…
idea that inherited characteristics of offspring are intermediate between maternal and paternal characteristics
oogenesis differs from spermatogenesis in that oogenesis :
leads to sex cells, if fertilized, will contribute mtDNA to the zygote
begins in fetal life
usually produces only one mature ovum at any one time
the genetic information is coded by the sequence of codons. each codon is made up of 3….
nucelotides
the nuclear dna molecule controls the manufacture of proteins by the following process:
the appropriate code is copied and transported by messenger RNA to the site of protein manufacture
Somatic cells are characterized by all the following
each includes a nucleus,
they are used in multiple tissues throughout the body
each contains a complete copy of all organism’s DNA.
The genetic code is based on ….
the particular sequence of nucleotides
what is mitosis
a body cell and its nucleus divides once and produce two identical cells.
what is meiosis
a reproductive cell and its nucleus divide twice and produce four cells- two pairs of identical cells with half the number of chromosomes
what is mendelian inhertiance
Mendelian inheritance is a type of biological inheritance that follows the laws originally proposed by Gregor Mendel in 1865 and 1866 and re-discovered in 1900. These laws were initially controversial.
what is true-breeding
A true-breeding organism, sometimes also called a purebred, is an organism that always passes down certain phenotypic traits to its offspring of many generations.
what is a hybrid
the offspring of two plants or animals of different species or varieties, such as a mule (a hybrid of a donkey and a horse).
what is recessive
relating to or denoting heritable characteristics controlled by genes that are expressed in offspring only when inherited from both parents, i.e., when not masked by a dominant characteristic inherited from one parent.
what is dominant
Dominance in genetics is a relationship between alleles of one gene, in which the effect on phenotype of one allele masks the contribution of a second allele at the same locus. The first allele is dominant and the second allele is recessive.
what is principle of segregation
the principle, originated by Gregor Mendel, stating that during the production of gametes the two copies of each hereditary factor segregate so that offspring acquire one factor from each parent.
what is the principle of independent assortment
Law of independent assortment is for polyhybrid Traits i.e. More than one trait,it states that all the different traits in an organism are acquired independent of each other,they are not dependent on a particular trait
Here we are comparing the color and shape of the peas
R -round shape(dominant)
r-wrinkled shape
Y-yellow color (dominant)
y-green color
law of segregation again
Law of segregation is for monohybrid inheritance i.e. A single trait.Each parent had two alleles for a particular trait.During gamete production the two copies of each hereditary factor segregate so that the offspring acquires one factor from each parent which is in accordance to the fact that the offspring will bear only 46 chromosomes (23 from mother and 23 from father)
Here in the Punnett square we are comparing dominant T (tall) and recessive t (short ) trait
So we see 16 different possibilities because color and shape are independent of each other
bigger punnet square with lotso stuffs
what is a trait
a distinguishing quality or characteristic, typically one belonging to a person.
a genetically determined characteristic.
what is a locus
A locus (plural loci) in genetics is a fixed position on a chromosome, like the position of a gene or a marker (genetic marker). Each chromosome carries many genes; human’s estimated ‘haploid’ protein coding genes are 19,000–20,000, on the 23 different chromosomes.
what is an allele
an allele is a variant form of a gene
When the copies of a gene differ from each other, they are known as alleles. A given gene may have multiple different alleles, though only two alleles are present at the gene’s locus in any individual.
what is homozygous
having two identical alleles of a particular gene or gene
what is heterozygous
having two different alleles of a particular gene or genes.
what is autosomes
any chromosome that is not a sex chromosome.
An autosome is a chromosome that is not an allosome (a sex chromosome). … The DNA in autosomes is collectively known as atDNA or auDNA.
what is a sex chromosome
a chromosome involved with determining the sex of an organism, typically one of two kinds.
What are sex chromosomes? What determines whether a person is male or female
X and Y chromosomes; Females have two X chromosomes; males have one X and one Y chromosome
An individual has two sets of chromosomes called homologous chromosomes, having one set from his mother and one from his father. Homologous chromosomes are similar in ___.
shape, size, genetic content
What is a homologous chromosome
Homologous chromosomes are chromosome pairs (one from each parent) that are similar in length, gene position, and centromere location. The position of the genes on each homologous chromosome is the same, however, the genes may contain different alleles.
Chromosomes that have the same sequence of genes and the same structure
what is genetic recombination
the exchange of genetic material between different organisms which leads to production of offspring with combinations of traits that differ from those found in either parent.
what is genetic recombination
the process by which the combinations of alleles for different genes in two parental individuals become shuffled into new combinations in offsprings individuals.
what is the human genome project
The Human Genome Project was an international scientific research project with the goal of determining the sequence of nucleotide base pairs that make up human DNA, and of identifying and mapping all of the genes of the human genome from both a physical and a functional standpoint.
what is the human genome project
A research effort undertaken to sequence all of our DNA and locate within it all of the functionally important sequences, such as genes
what is nondisjunction
the failure of one or more pairs of homologous chromosomes or sister chromatids to separate normally during nuclear division, usually resulting in an abnormal distribution of chromosomes in the daughter nuclei.
What is Nondisjunction and how does it occur?
If nondisjunction occurs during anaphase II of meiosis II, it means that at least one pair of sister chromatids did not separate. In this scenario, two cells will have the normal haploid number of chromosomes. Additionally, one cell will have an extra chromosome (n + 1) and one will be missing a chromosome (n - 1)
Down Syndrome: trisomy 21
It results from one of the most common chromosomal abnormalities in humans, the presence of an extra chromosome 21 in each cell or rarely part of the cells of the body.
Extra copy of chromosome 21. Down syndrome is the most common single cause of human birth defects.
usually caused by an error in cell division called “nondisjunction.” Nondisjunction results in an embryo with three copies of chromosome 21 instead of the usual two.
what is a somatic cell
any cell of the body except sperm and egg cells. Somatic cells are diploid, meaning that they contain two sets of chromosomes, one inherited from each parent. … a mammalian blastula in which some differentiation of cells has occurred.
any cell other than a gamete, has 46 chromosomes, body cells.
what is a gamete
A sex cell that contains the haploid of chromosomes
reproductive cells, sperm or egg
A haploid cell such as an egg or sperm. Gametes unite during sexual reproduction to produce a diploid zygote.
meiosis again
(genetics) cell division that produces reproductive cells in sexually reproducing organisms
sex cells
Gametes- sperm and egg cells. Made by meiosis with ½ the regular number of chromosomes in them.
haploid
An organism or cell having only one complete set of chromosomes
what is a zygote
The one cell that is formed when the cell accepts the sperm cell.
The fertilized egg, which is diploid, that results from the union of haploid gametes during fertilization
the fertilized egg; it enters a 2-week period of rapid cell division and develops into an embryo. (Myers Psychology for AP 2e p. 466)
what is 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.
example of codominance???
When two alleles for a trait are equally expressed with neither being recessive or dominant, it creates codominance. Examples of codominance include a person with type AB blood, which means that both the A allele and the B allele are equally expressed.
what is diploid
(genetics) an organism or cell having two sets of chromosomes or twice the haploid number
Diploid vs. haploid???
DIP: (genetics) an organism or cell having two sets of chromosomes or twice the haploid number
HAP: (genetics) an organism or cell having only one complete set of chromosomes
What is Pleiotropy and give an example
Pleiotropy refers to the phenomenon in which a single gene controls several distinct, and seemingly unrelated, phenotypic effects.
A classic example of pleiotropy is the human disease PKU (phenylketonuria).
what is pleiotrophy
Definition:
Determination of more than one phenotype by a single gene pair (Affected by environmental conditions)
genotype + environment ⇒ phenotype -light, temperature, nutrition
Example: -coat color of Siamese cat -1 pair of genes for coat color -warm areas of body- light color -cool areas of body- dark color -extremities cooler than core so they are darker
-Changing temperature can change color
what are linked genes???
genes that are on the same chromosome
genes on the same chromosome with other genes; cannot undergo independent assortment and ratio is usually 1:2:1
law of independent assortment again lmao
the law linked genes dont follow because they are not on separate chromosomes
another recombination
production of offspring with new combinations of traits from parents
what is genetics
The scientific study of heredity
gamete again
specialized cell involved in sexual reproduction
truebreedintg again
erm used to describe organisms that produce offspring identical to themselves if allowed to self-pollinate
zygote =
FERTILIZED EGG
what are nucleic acids
Organic compounds in living organisms that are responsible for passing on hereditary information
what is rna
The type of nucleic acid that forms from DNA and functions with Ribosomes to form protein molecules
what is dna
The Nucleic acid that is located primarily in the nucleus
2 primary nucleic acids?
dna & rna
structure of dna =
It is a twisted ladder made of molecules
unique about dna is that
they set a template for themselves
unique about rn is that
Its base replaces thymine with uricel
what is the nucleus
The nucleus is the boss of the cell it carries dna and gives out instructions. It is charge of reprodutction and making protein it is double layered. nucleus. The nucleus is the boss of the cell it carries dna it is responsible for reproduction and making protein it also has two layers.
where is nucleus
centerrr1!!
what is cytoplasm
jelly like substance inside cell membrane that surrounds the nucleus and in which the organelles are suspended
FUNCTION: fluid that fills the cell and maintains the cell’s shape. Organelles are suspended in the cytoplasm, which can also store chemical substances. The extranuclear dna is in the mitochondria
what is a prokaryote
single-celled organisms with no nuclear membranes or organelles and with their genetic material as a single strand in the cytoplasm
what is the nucleus
a membrane bound structure in eukaryotic cells that contains the genetic material
what is eukaryotes
multicelled organisms tht have a membrane bound nucleus containing both the genetic material and specialized organisms
diploid again
a cell that has a full complement of paired chromosomes
haploid again
cell that has a single set of unpaired chromosomes; half of the number of chromosomes as a diploid cell
what is protein synthesis
Protein synthesis is the process whereby biological cells generate new proteins; it is balanced by the loss of cellular proteins via degradation or export.
what are structural proteins
proteins that form an organisms physical attributes
what are regulatory proteins
proteins involved in the expression of control genes
what is recombination
the exchange of genetic material between homologous chromosomes from a cross-over event
what are haplotypes
a group of alleles that tend to be inherited as a unit due to their closely spaced loci on a single chromosome
what is mitochondria
energy producing (ATP) organelles in eukaryotic cells ; they posses their own independent DNA
what are antigens
specific proteins, on the surface of cells, that stimulate the immune system’s antibody production
what are antibodies
molecules that form as part of the primary immune response to the presence of foreign substances; they attach to the foreign antigens
what are nucelotides
building block of dna and rna composed of sugar, a phosphate group, and one of four nitrogen bases.
what are amino acids
organic molecules combined in a specific sequence by the ribosomes to form a protein
what is messenger RNA ( mRNA)
the molecules that are responsible for making a chemical copy of a gene needed for a specific protein; that is, for the transcription phase of protein synthesis
what is codons
the sequences of 3 nitrogen bases carried by mRNA that are coded to produce a specific protein and are transcribed and translated during protein synthesis
what is transfer RNA (tRNA)
the molecules that are responsible for transporting amino acids to the ribosomes during protein synthesis
what is a gene
basic unit of inheritence; a sequence of DNA on a chromosome, coded to produce a specific protein
what are structural genes
genes coded to produce particular products, such as an enzyme or hormone, rather than regulatory proteins
what are regulatory genes
those genes that determine when structural genes and other regulatory genes are turned on and off for protein synthesis
whaT ARE species
a group of related organisms that can interbreed and produce fertile, viable offspring
what is gene pool
all the genetic information in the breeding population
what is mutation
a random change in a gene or chromosome, creating a new trait that advantageous, deleterious, or neutral in its effects on the organism
what is point mutation
replacements of a single nitrogen base with another base , which may or may not affect the amino acid for which the triplet codes
spontaneous mutation
random changes in the dna that occur during cell division
what is induced mutation
refers to those mutations in the DNA resulting from exposure to toxic chemicals or to radiation
what is gene flow
admixture, or the exchange of alleles between 2 populations
what is genetic drift
the random change in the allele frequency from one generation to the next , with greater effect in small populations
what is endogamous
refers to a population in which individuals breed only with other members of the population
what is exogamous
refers to a population in which individuals breed only with nonmembers of their population
what is microevolution
small scale evolution such as changes in allele frequency, that occurs from one generation to the next
what is macroevolution
large-scale evolution, such as a speciation event, that occurs after hundreds or thousands of generations
what is sickle-cell anemia
a genetic blood disease in which the red blood cells become deforemd and sickle-shaped, decreasing their ability to carry oxygen to tissues
what are proteins
Proteins are large biomolecules, or macromolecules, consisting of one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, responding to stimuli, and transporting molecules from one location to another.
what is mitochondrial dna
Mitochondrial DNA is the DNA located in mitochondria, cellular organelles within eukaryotic cells that convert chemical energy from food into a form that cells can use, adenosine triphosphate
what are enzymes
Enzymes are macromolecular biological catalysts. Enzymes accelerate chemical reactions. The molecules upon which enzymes may act are called substrates and the enzyme converts the substrates into different molecules known as products.
what are enzymes
proteins that speed up reactions by reducing the activation energy without being consumed in the reaction
what is a hemoglobin
A protein and the main cytoplasmic component of erythrocytes.
Oxygen carrying component of RBC
what is a hemoglobin
the protein molecule in red blood cells that carries oxygen from the lungs to the body’s tissues and returns carbon dioxide from the tissues back to the lungs.
what are hormones
Hormones are the body’s chemical messengers and are part of the endocrine system.
what are hormones
any member of a class of signaling molecules produced by glands in multicellular organisms that are transported by the circulatory system to target distant organs to regulate physiology and behaviour.
what is a structural gene
a gene that codes for any RNA or protein product other than a regulatory factor (i.e. regulatory protein)
what is a structural gene
Genes that code for particular polypeptide are called structural genes. (part of an operon)
what are regulatory genes
Codes for transcription factors that regulate transcription of the operon.
what are regulatory genes
A regulator gene, regulator, or regulatory gene is a gene involved in controlling the expression of one or more other genes.
what are homeotic genes
In evolutionary developmental biology, homeotic genes are genes which regulate the development of anatomical structures in various organisms such as echinoderms, insects, mammals, and plants.
what are homeotc genes
master control genes that regulate groups of other genes that determine what body parts will develop in which locations
what are polygenic traits
Polygenic traits are those traits that are controlled by more than one gene. Such traits may even be controlled by genes located on entirely different chromosomes. Human height, eye and hair color are examples of polygenic traits. Skin color is another polygenic trait for humans and a variety of other animals.
what is abo blood type system
The ABO blood group system is used to denote the presence of one, both, or neither of the A and B antigens on erythrocytes.
what is reproductive isolation
Crosses between an infected population and one free from infection produces a nearly total reproductive isolation between the semi-species. However, if both species are free from the bacteria or both are treated with antibiotics there is no reproductive barrier.
define reproductive isolation
the existence of biological factors (barriers) that impede members of 2 species from interbreeding and producing viable fertile offspring
what is a mutagen
a mutagen is a physical or chemical agent that changes the genetic material, usually DNA, of an organism and thus increases the frequency of mutations above the natural background level. As many mutations can cause cancer, mutagens are therefore also likely to be carcinogens, although not always necessarily so
what is population bottleneck
A population bottleneck or genetic bottleneck is a sharp reduction in the size of a population due to environmental events or human activities
what is geographic isolation
refers to two population of the same species being separated due to some type of physical barrier. This separation of population occurs when a body of water or land forms and divides a habitat.
what is founder principle
he conditional probabilities of the frequencies of a set of genes at any future date depend on the initial composition of the founders of the population and have in general no tendency to revert to the composition of the population from which the founders were themselves derived.
how many chromosomes are there in a normal human cell?
46
why do we conduct studies of genetics at the level of the cell
cell = basic unit of life for all organisms
understand the basic cell structure
center = nucleus
red multiple ovals = mitochondria
spaghetti connected to the nucleus = endoplasmic reticulum
wall around cell = cell membrane
what is the unit of evolution
reproductive population
what is the gene pool of a population
the sum of all alleles carried by the members of a population
what is the largest reproductive population
species
define evolution
a change in the gene pool of a population; it indicates an alteration in the frequency of alleles
4 factors that produce and redistribute variation (Mechanisms of Evolutionary Change)
mutations
natural selection
genetic drift
geneflow
natural selection is a process of a factor that brings
about change to the frequency of alleles in the gene pool of a population
