Genetics Flashcards
Genetics
What is sperm formation
Diploid spermatognia divide by mitosis to produce primary spermocytes. Primary spermocytes divide by meiosis to produce four functional cells called spermatids. These spermatids then undergo differentiation to become sperm cells
What is egg formation
Oogonia divide by mitosis to produce primary oocytes. Primary oocytes divide by meiosis to form one egg and three polar bodies. Therefore only ONE functional egg is produced because division of cytoplasm is not equal.
What is 1 abromality that effects the chromosomes
- Duplication
- duplication causes the repetition of a segment
Ex
Normal- VW-XYZ
Duplication- VW-XXYZ
What is 2 abromality that effects the chromosomes
Deletion
- Deletion causes the removal of a segment
Ex
Normal - VW-XYZ
deletion - VW -YZ
What is 3 abromality that effects the chromosomes
Inversion
- Inversion reverses the proper order of the genetic information (XYZ)
- Ex
Normal- VW-XYZ
inversion - VW-ZYX
What is 4 abromality that effects the chromosomes
Translocation
- translocation moves a segment from one chromosome to a non homologous one
Ex
Normal - ABCD-VW-XYZ
Translocation- AB-XYZ-VW-CD
What is non disjunction
Non disjunction is the failure of chromosomes to separate or move apart during meiosis
What is non disjunction in meiosis 1 and how is it diffrent than meiosis 2
Non disjunction in meiosis 1 is the separation of homologous chromosomes and resulting in aneuploidy (too many or too few chromosomes) this resulting in two gametes with an extra chromosomes and two missing a chromosome. None of the gametes are correct
What is non disjunction in meiosis 2 and how is it different than meiosis 1
Non disjunction in meiosis 2 is the separation of the sister chromatids resulting in half the gametes being normal and a monosomy(missing a chromosome) and polysomy(extra chromosomes)
What is a karyotype
A karyotype is a picture of all 46 chromosomes that is used to collect information regarding characteristics. When the cells are dividing they thicken and scientists use a chemical that stops mitosis at metaphase. Cells are then fixed, stained and pictures are taken with a microscope so that chromosomes are visible to naked eye. They are then stored in homologous pairs based on their size, banding patter, and centromere location.
How do you determine the sex of a human through chromosomes?
Humans have 46 chromosomes
22 identical pairs (Autosomes)
1 sex paid (sex chromosomes)
A female posses:
1 pair of XX chromosomes
A male posses:
1 pair of XY chromosomes
Male sperm can carry Y or X and that is what determines the sex of baby
What is amniocenteses
Amniocentesis is a genetic screening method. It involves a needle that is used to pull cells (centrifuged cells) from the amniotic fluid while the baby is still in the womb and is karyotypes for any chromosomal diseases or abromalitys on a certain chromosome (trisomy 18) and the sex of the baby.
What is IVF
In vitro fertilization is when mature eggs are collected from the overease and sperm is used to fertilize that egg in a dish. Scientists will screen these fertilized eggs to find one without any abromalitys as this is a way for people with genetic problems or older people to have children. The egg (zygote) is the placed back into the uterus of the woman.
What is polyploidy and how does it help certain things
Polyploidy is a condition in which an individual has sets of chromosomes greater than the normal diploid number (3n 4n etc) polyploids with even numbers are fertile as pairs can be formed but odd numbers are sterile as pairs cannot be formed. They are usually larger plants, make larger fruit, more vigorous. Animals that are polyploidy include salamanders, frogs, leeches and some fish. There is one mammal polyploidy called argentenian rat
Theory of inheritance 1 by Artisole (384 BCE)
It was the first widely accepted theory of inheritance called pengensis. The egg and speed consist of particles called pangenes, from all parts of the body.
Theory of inheritance 2 (1667) Anthony Van Leeuwenhoek
He discovered living sperm in semen. He believed he saw a complete miniature person in the head of sperm. Came from father developed in mother.
Theory of inheritance 3 (1800)
It was believed offspring would have characteristics of both parents. They thought the characteristics would blend somewhere in the middle. They believed that original characteristics of the parents could not be perfectly passed down to offspring.
Who was Gregory Mendel
Gregory Mendel (1822-84)was an Austrian monk that studied botany and mathematics at the university of Vienna before entering the monastery.
Why was Gregory Mendel so successful?
He used his knowledge in botany and mathematics. He also chose a pea plant. Pea plants were available in many varsities and show different traits. He also took advantage of the fact that pea plants can produce sexually but can also self fertilize. He used this to insure that the plants he studied were pure bred. He true bred through selective breeding. He used a paint brush to control his experiments so he could breed certain plants with others. (Cross breeding )
What is a genotype
The combination of Alleles for any given trait, or genetic make up.:
What is a phenotype
It is the actual visible and physical characteristics of an organism
What is a monohybrid cross
A monohybrid cross is a cross in which both parents are heterozygous for a single trait.
(Rr,Rr)
Genotypic ratio 1:2:1
Phenotypic ratio: 3-1
What is a dihybrid cross
A dihybrid cross is a cross in which both alleles are heterozygous for both traits
(TtRr,TtRr)
Phenotypic ratio: 9:3:3:1
Genotypic ratio : 4: 4 (2) : 4 (1)
What is a test cross
A test cross is used to determine if a n organism is pure bred. This is done by crossing it with a homozygous recessive organism.
(Tt,tt)
Phenotype: all bark and 50/50
What is Mendels law of segregation
Mendels law of segregation is only one of two gene copies present in an organism is distributed to each gamete.
What is mendels law of independent assortment
During gamete formation, the two alleles for one gene assort independently of the alleles for other genes.
What is down syndrome and what are the effects?
Trisomy 21 is when someone has an extra chromosome (47).it is one of the few trisomy disorders in which a child has a high probability of living to adulthood. Some effects are short stature, intellectual disability, reduced life span, characteristic features. Identify by three 21 chromosomes.
What is Kleinfelters syndrome
Klinefelter syndrome ( trisomy XXY) is when a male has an extra sex chromosome (X) the man will be XXY instead of XY. They will now have 47 chromosomes. Some effects of this are they may be sterile, produce less testosterone, taller than average, often don’t know until they are tested. Identify by two X one Y.
What is XYY syndrome
XYY syndrome is a male with an extra Y chromosome. This male will have an extra chromosomes (47). Some effects of this are, taller than average, produce high levels of testosterone, may have sterility problems, don’t know until tested. Identify by two Y.
What is Turner syndrome
Turner syndrome is when a female only has 1 X chromosome (X0). This female is missing her second sex chromosome. This is the only monosomy in which the embryo survives. This results in 45 chromosomes, some effects are delayed puberty due to low levels of estrogen, shorter than average (4’8”), low set ears. Identify by one X.
What is a pedigree and how do they work
A pedigree is a diagram which shows the appearance of a certain phenotype from one generation to the next, the genotypes can then usually be determined.
Each generation is represented by a Roman numeral
Each individual has a number
Males are squares
Females are circles.
Dark means affected and white means it mus at least have one dominant trait
What are the three types of pedigrees and how to determine which one?
- Autosomal recessive- affected people won’t appear in every generation and will have half and half’s
- Autosomal dominant- affected individuals in every generation, will only be homo,
- X linked - skip generations, mostly males, no father to son transmission (a o with a dot means daughter is carrier)
Who are dizygotic twins and monozygotic twins? How are they diffrent?
Dizygotic are non identical twins (no line inbetween) and we’re formed by two different sperm
Monozygotic are identical twins (whith line) were somewhere along the way separate
What is the best blood type to be for giving and receiving?
The best for giving is type O because it does not have any markers while type AB is the best to have because it can accept all other types of blood because it has all markers.
What do the cells in the body that undergo mitosis
Somatic cells are diploid
What are the three main phases Of the cell cycle
Interphase, mitosis and cytokinesis
What occurs during the S phase of interphase
During S phase of interphase the cellular info is copied and replicate, the dna exists as chromatin
What are two ways you can visually identify prophase
Thick strands of DNA lose in the cell and no nucleolus
What are two ways to visually identify metaphase
Chromatids condense into chromosomes, and line up in the middle of cell
What are two ways to visually identify anaphase
Homologous chromosomes separate and are pulled to poles of the cell
What are two ways to visually identify telophase
Spindle fibres disappear and nucleolus form around chromosome
What are the differences between cytokinesis in animals and plants?
Animals from a cleavage furrow and plants form a cell plate
What are mutagens ?
Mutagens cause mutations in our dna and may lead to cancer (X ray, chemicals, UV light)
How do cancer cells differ from normal cells?
Cancer cells don’t mature, or become specialized and spend much more time in mitosis dividing uncontrollably.
What are diploid and haploid cells
Mitosis cells go from diploid to diploid but form 2 cells while meiosis diploids form 4 new cells haploid
What is synapsis
Synapsis is the pairing of two chromosomes in meiosis before crossing over. Propase 1 of meiosis 1
What is a tetrad
When they cross over 4 homologous chromatins or 2 homologous chromosomes
What is the summary of meiosis
Meiosis only occurs in sex cells (gametes) in prophase 1 the homo chromosomes will pair up and exchange parts (crossing over) in metaphase 1 the homologous will randomly line up at middle of cell this is called random assortment. These are both meant for high genetic variability. In anaphase 1 the homologous chromosomes separate. meiosis 2 is very similar to mitosis, but in anaphase 2 the sister chromatids separate.
What are the numbers of divisions and number of cells formed in mitosis Vs. Meiosis
Number of divisions in mitosis: 1
Meiosis: 2
Number of cells formed
Mitosis: 2
Meiosis: 4
What is aneuploidy
Aneuploidy is too many or too little chromosomes. A number that is not an exact number multiple of haploid.
What is a mutation
Mutation is the altering of the DNA sequence or genetic make up of someone’s DNA
Example of genetic defect caused by a single gene defect
Sickle cell anemia (X)
Is the mother or father determine the sex of a child
The father because he can give an X or Y while the mothers egg is an X
The 5 reasons for mendels success
1 use of mathematics and probability’s
2. Able to control the pollination of the pea plant
3. Plants matured quickly producing many seeds, therefore he could study many generations in a short period of time
4. Pea plants has many traits that appears in one of two forms that wren easily distinguishable (tall dwarf)
5. He repeated his crosses numerous times
What is an example of a singe cell Defect
Sickle cell anemia
What is the difference between polysomy and polyploidy
Polysomy means too many chromosomes
Polyploidy means a whole extra set of chromosomes (3n 4n)
