Bio 1201 Chapter 11, 24 Flashcards
Blending concept of inheritance
- Parents of contrasting appearance produce offspring of intermediate appearance
- Over time, variation would decrease as individuals became more alike in their traits.
- blending was a popular concept during Mendel’s time.
who formulated the theory of inheritance?
mendal
Inheritance involves what?
reshuffling of genes from generation to generation
Who is is Greg mendal
An Austrian monk, who at the time of his experiments was a substitute science teacher at a local high school
What was Greg Mendel like?
- had many interests
- had background in mathematics that promotes him to apply statistical methods and laws of probability to his breeding experiments
- was very careful- deliberate, followed the scientific methods very closely and kept detailed, accurate records
- was prepared-carefully and conducted many preliminary studies with various animals and plants.
What did the 2 laws of Mendel describe?
the behavior of these “particular units of heredity” as they are passed from one generation to the next
why did Mendel use gardening peas
Easy to cultivate
Short generation time.
Although peas normally self-pollinate (pollen only goes to the same flower), they could be cross-pollinated by hand by transferring pollen from the anther (male part of a flower) to the stigma (female part of a flower).
Easy to measure:
seed shape, seed color, and flower color.
Law of Segregation
Mendel chose varieties that differed in only one trait (e.g., plant height).
If the blending theory of inheritance were correct, the cross should yield plants with an intermediate appearance of medium height compared to the parents, which were all tall or all short
punnet square
Visually presents Mendelian inheritance
It is a diagram of a breeding cross and displays the possible combinations
what does a punnet square show?
It gives probability for genotype, not phenotype
genotype
It refers to the two alleles an individual has for a specific trait.
phenotype
It refers to the physical appearance of the individual.
alleles
Different versions of a gene
locus
lactation of allele
what represents DNA sequences that code for proteins.
The dominant and recessive alleles
The dominant allele codes for
the protein associated with the normal gene function within the cell.
The recessive allele represents a
“loss of function.”
what happens During meiosis I
the homologous chromosomes separate.
The two alleles separate from each other.
what does the the process of meiosis explain?
The process of meiosis explains Mendel’s law of segregation and why only one allele for each trait is in a gamete
Monohybrid Crossing
Cross of one gene, between individuals who have different alleles
Dihybrid Crossing
Cross of two or more genes
To use punnett square for dihybrid cross, the genes must be independent of each other (independent assortment)
what does a dihybrid cross use?
true-breeding plants differing in two traits.
Mendel tracked each trait through two generations
law of independent assortment.
The pair of factors for one trait segregate independently of the factors for other traits.
All possible combinations of factors can occur in the gametes
Testcrosses
determines the genotype of an individual having the dominant phenotype
Genetic disorders
are medical conditions caused by alleles inherited from parents.
Autosome
is any chromosome other than a sex chromosome (X or Y)
Genetic disorders caused
by genes on autosomes are called autosomal disorders.
Some genetic disorders are autosomal dominant.
Other genetic disorders are autosomal recessive.
Autosomal Recessive Patterns of Inheritance
If both parents carry one copy of a recessive gene they are unaffected but are capable of having a child with two copies of the gene who is affected.
Methemoglobinemia
It is a relatively harmless disorder.
Accumulation of methemoglobin in the blood causes skin to appear bluish-purple.
Cystic Fibrosis
Mucus in bronchial tubes and pancreatic ducts is particularly thick and viscous.
Most common lethal genetic disease affecting Caucasians
Dr. Council’s Dissertation Topic— Why is this build up bad?
Autosomal Dominant Patterns of Inheritance and Disorders
Two parents with a dominantly inherited disorder will be affected by one copy of the gene.
It is possible for them to have unaffected children.
Osteogenesis Imperfecta
Characterized by weakened, brittle bones.
Most cases are caused by mutation in genes
required for the synthesis of type I collagen.
Hereditary Spherocytosis
It is caused by a mutation in the
ankyrin-1 gene.
Red blood cells become spherical,
are fragile, and burst easily
multiple alleles (multiple allelic traits
Some traits are controlled by these-
The gene exists in several allelic forms, but each individual only has two alleles.
example of multiple alleles
The ABO blood type
an example of codominance.
The ABO blood type More than one allele is fully expressed.
Both IA and IB are expressed in the presence of the other.
Incomplete Dominance
Heterozygote has a phenotype intermediate between that of either homozygote.
Homozygous red has red phenotype.
Homozygous white has white phenotype.
Heterozygote has pink (intermediate) phenotype.
what does phenotype reveal
genotype without a testcross.
Familial Hypercholesterolemia (FH)
examples of incomplete dominance:
Homozygotes for the mutant allele develop fatty deposits in the skin and tendons and may have heart attacks during childhood.
Heterozygotes may suffer heart attacks during early adulthood.
Homozygotes for the normal allele do not have the disorder
Incomplete penetrance
The dominant allele may not always lead to the dominant phenotype in a heterozygote.
Many dominant alleles exhibit varying degrees of penetrance.
polydactyly
There are extra digits on hands, feet, or both.
Not all individuals who inherit the dominant polydactyly allele will exhibit the trait.
Pleiotropy
occurs when a single mutant gene affects two or more distinct and seemingly unrelated traits.
Marfan syndrome
has been linked to a mutated gene FBN1 on chromosome 15 which codes for the fibrillin protein.
Disproportionately long
arms, legs, hands, and feet
A weakened aorta
Poor eyesight
Polygenic Inheritance
Occurs when a trait is governed by two or more sets of alleles.
Each dominant allele has a quantitative effect on the phenotype.
These effects are additive.
It results in continuous variation of phenotypes within a population.
The traits may also be affected by the environment.
Polygenic Inheritance examples
Human skin color
Height
Eye color
X-Linked Inheritance
genes that have nothing to do with gender.
X-linked genes are carried on the X chromosome.
The Y chromosome does not carry these genes.
when was x-linked inheritance discovered and by who?
It was discovered in the early 1900s by a group at Columbia University, headed by Thomas Hunt Morgan.
how did Thomas hunt Morgan discover x-linked inheritance
Performed experiments with fruit flies
They can be easily and inexpensively raised in simple laboratory glassware.
Fruit flies have the same sex chromosome pattern as humans.
Morgan’s experiments with X-linked genes apply directly to humans.
Several X-linked recessive disorders occur in humans
Color blindness
The allele for the blue-sensitive protein is autosomal.
The alleles for the red- and green-sensitive pigments are on the X chromosome.
Menkes syndrome
It is caused by a defective allele on the X chromosome.
It disrupts movement of the metal copper in and out of cells.
Phenotypes include kinky hair, poor muscle tone, seizures, and low body temperature.
Muscular dystrophy
Causes wasting away of the muscle
It is caused by the absence of the muscle protein dystrophin.
Adrenoleukodystrophy
It is an X-linked recessive disorder.
It is a failure of a carrier protein to move either an enzyme or very long chain fatty acid into peroxisomes.
Hemophilia
It is an absence or minimal presence of clotting factor VIII or clotting factor IX.
An affected person’s blood either does not clot or clots very slowly
Hemophilia is called the
bleeder’s disease because the affected person’s blood either doesn’t clot correctly or doesn’t clot at all.
People with hemophilia bleed internally and externally after injury.
Blood transfusions or clotting factor injections help with the disorder.
The pedigree shows why hemophilia is referred to as
Queen Victoria was the first of the royals to carry the gene.
Eventually it was spread throughout the royal families of Europe through arranged marriages between the English, Spanish, Prussian, and Russian royal families.
meristem
When a plant embryo first develops, first cells are meristem cells.
Undifferentiated cells able to divide indefinitely and give rise to many types of differentiated cells.
Allows flowering plants to grow throughout their lifetime.
Apical meristems
at the tips of stems and roots increase the length of these tissues.
Apical meristems produce three types of meristem, which produce three specialized tissues.
Xylem
transports water and minerals from the roots to the leaves.
Tracheids
They are long with tapered ends.
Water moves across pits in end walls and side walls.
Vascular rays between rows of tracheids conduct water across the width of the plant
Vessel Elements
They are larger, with perforation plates in their end walls.
They form a continuous vessel for water and mineral transport.
Phloem
transports sucrose and other organic compounds from the leaves to the roots.
Sieve-tube members
function as conducting cells.
Contain cytoplasm, but lack nuclei
Sieve plate – cluster of pores in wall
Vegetative organs
are all plant parts except reproductive structures.
Vegetative organs are concerned with growth and nutrition.
A typical plant features three vegetative organs.
Roots, stems, and leaves
Most flowering plants possess what systems
root and shoot
root system
simply consists of the roots.
shoot system
consists of the stem and leaves.
structures involved in reproduction.
Flowers, seeds, and fruits
Shoot system of a plant is composed of
stem, branches, and leaves.
Stem
is the main axis of a plant that elongates and produces leaves
Nodes
occur where leaves are attached to the stem.
Internode
is the region between nodes.
Stem also has
vascular tissue that transports water and minerals
Foliage leaves
usually broad and thin.
Blade
Wide portion of foliage leaf
Petiole
Stalk attaching blade to stem
Leaf Axil
Upper acute angle between petiole and stem where the axillary bud is found
Tendrils
Leaves that attach to objects
Bulbs
Leaves that store food
Variations of organs and organ systems
Monocots and Eudicots
Monocots
Cotyledons act as transfer tissue.
Nutrients are derived from the endosperm.
Root vascular tissue occurs in a ring.
Leaves have a parallel venation.
Flower parts are arranged in multiples of three.
Eudicots
(Two cotyledons)
Cotyledons supply nutrients to seedlings.
Root phloem is located between xylem arms.
Leaves have a netted venation.
Flower parts are arranged in multiples of four or five.
cotyledon
is a significant part of the embryo within the seed of a plant. Upon germination, the cotyledon usually becomes the embryonic first leaves of a seedling.
Annual plants
live for only one growing season.
These produce enough vegetative structures to support flower and seeds.
After seed dispersal, the plant dies.
Perennial plants live for three or more seasons.
These spend energy making vegetative structures which help the plant survive for years.
the difference between annuals and perennials.
Flower-inducing genes LEAFY and Apetala 1 They are genetic switches which determine whether a plant is an annual or a perennial.
Blocking flower-inducing genes in annuals induces perennial growth.
Primary root (taproot
Fleshy, long single root, that grows straight down
Stores food
Fibrous root system
Slender roots and lateral branches
Anchors plant to soil
Found in monocots
Adventitious roots
Roots develop from organs of the shoot system instead of the root system
Prop roots
Epiphytes
which live in or on trees, have aerial roots.
Mycorrhizae
Mutualistic associations between roots and fungi
Assist in water and mineral extraction
Root nodules
Contain nitrogen-fixing bacteria
Plants cannot extract nitrogen from air but bacteria in nodules can take up and reduce atmospheric nitrogen.
Plants get nitrogen from bacteria, which receive carbohydrates from the plant.
Stolons
Aboveground horizontal stems
Produce new plants when nodes touch the ground
Rhizomes
Underground horizontal stems
Contribute to asexual reproduction
Variations:
Tubers – Enlarged portions functioning in food storage
Corms – Underground stems that produce new plants during the next season
Humans make use of stems
Sugar cane produces table sugar.
Cinnamon and quinine are produced from bark.
Wood is used to produce paper and building materials.
Wood
secondary xylem that builds up year after year.
Annual ring
is made up of spring wood and summer wood.
Summer wood has a lower proportion of vessels than spring wood.
Foliage leaves
are usually broad and thin
Blade
Wide portion of foliage leaf
Petiole
Stalk attaching blade to stem
Tendrils
Leaves that attach to objects
Bulbs
Leaves that store food
deciduous.
Plants that lose all of their leaves
Upper and lower epidermis
Waxy cuticle
Trichomes
Lower epidermis has stomata for gas exchange.
Mesophyll
Eudicot leaves have:
Palisade mesophyll containing elongated cells
Spongy mesophyll containing irregular cells bounded by air spaces
Contains many chloroplasts
3 particles from largest to smallest
sand, silt, and clay
Hydrogen ions
move by a proton pump and the breakdown of ATP
Cation like K+
move by chemiosis
Negatively charged minerals like NO3
move by co-transport
