Genetics Lab Flashcards
The is a type of cell division which
takes place in a reproductive cell
(diploid) and produces four unique
haploid daughter cells
meiosis
sub-phases of meiosis
Reduction Meiosis (MI) & Equatorial Meiosis (MII)
separation of homologous chromosome
Reduction Meiosis (MI)
separation of sister chromatids
Equatorial Meiosis (MII)
- Production of gametes
- Maintain the ploidy level of each
generation
importance of meiosis
is a term referring to the number of chromosome sets in somatic cells of the diplophase (2n) or gametophytic cells of the haplophase (1n).
ploidy level (X)
_________ cells have two sets of chromosomes
and are indicated by 2x.
diploid
Five Sub-phases of Prophase I
L – Leptonema ( thicken chromosome)
Z – Zygonema (synapsis)
P – Pachynema ( crossing-over)
D – Diplonema (chiasmata)
D – Diakinesis
- The chromosomes thicken and
become visible, but the
chromatids remain invisible. - The centrosome begin to move
towards the opposite poles
Leptotene/Leptonema
Homologous chromosomes enter
synapsis (the fusion of homologous
chromosome) forming the
synaptonemal complex.
Zygotene/Zygonema
________ (stabilized pairing of homologous chromosomes)
synapsis
______(facilitates genetic exchange between homologs)
crossing over
______(ensures proper chromosomal alignment)
Chromosomal alignment
Synaptonemal complex essential
for:
Synapsis
Crossing over
Chromosomal alignment
Regulates meiotic recombination
The synapsis is complete all throughout each pair of homologous chromosomes.
Pachytene/Pachynema
The synaptonemal complex dissolves.
Diplotene/Diplonema
The _____ or four chromatids of the
homologous pair is visible.
tetrad
Crossing over points appear as _____ (holding of non-sister chromatids together).
chiasmata
- The chromatids thicken and shorten.
- At the end of prophase I, the nuclear envelop breaks down and the spindle fibers begins to
form
diakinesis
- Tetrads line up along the metaphase plate.
- The centromere of each homologous chromosomeis attaches to centrosome in each
opposite pole by microtubule.
Metaphase I
The homologous chromosomes move
to the opposite poles.
Anaphase I
- Each complement of the homologous pair reaches the opposite poles.
- The nuclear envelop reforms
Telophase I
separates the daughter cells.
Cytokinesis
______ is alternative form of the gene
Allele
______ separation homologous chromosome
Haploid (n)
- The chromosomes condense.
- The centrosomes appears in each the opposite poles of the cell.
- The nuclear envelope
breaks down at the end of
this phase.
Prophase II
- The centromeres of each sister chromatids are attach to the microtubules connected to the centrosome located on the opposite poles of the cell.
- Each chromosome aligns at the metaphase plate.
Metaphase II
- The sister centromeres detach from each other.
- Sister chromatids to move to opposite poles
Anaphase II
- Each individual sister chromatids begins to uncoil.
- The nuclear envelopes reform.
Telophase II
proceeds producing four unique daughter
cells.
cytokinesis
Exchange of chromosome segments between homologous chromosomes during crossing over in the Pachytene stage
Recombination
Essential in creating variation among individual in the same species through producing unique gametes (sex cells)
Genetic Implication
a unit of heredity; a section of DNA which encodes for a protein
Gene
the entire set of genes in an organism
Genome
specific type or variant of genes that occupy the same position on homologous chromosomes and that cover the same trait (like ‘flavors’ of a trait).
Alleles
a fixed location on a strand of DNA where a gene or one of its alleles is located (address of a gene)
Locus
the physical feature/observable traits resulting from the effects of genotype + environment + interaction of genotype and environment
(P = G+E+GxE)
Phenotype
specific combination of alleles for a gene of a particular trait (e.g. RR, Rr, rr)
Genotype (Narrow type)
genetic makeup of an organism
Genotype (broad sense)
gene combination involving identical alleles (BB, bb)
homozygous genotype
gene combination of involving different alleles (Bb, bB)
heterozygous genotype
is an individual having homozygous genotype. It may contain several genes in homozygous state due to repeat selfing generation.
Pure line
is an individual having heterozygous genotype and it is produce through crossing pure lines
hybrid
the parental generation in a breeding experiment.
Parent or P Generation
the offspring of the parental generation
F1 generation (1st filial generation)
the offspring of F1 generation
F2 generation (2nd filial generation)
______ is passing down or transmission of genetic material from one generation to the next generation through _______________
heredity; gametes formation/fertilization
Laws governing Inheritance of Traits
Law of Dominance (complete)
Law of Segregation
Law of Independent Assortment
▪ Austrian monk
▪ Studied the inheritance of traits in pea plants
▪ Father of Genetics
Gregor Mendel
Seven contrasting traits that Mendel studied in pea plants
Seed shape
seed color
pod shape
pod color
flower color
flower position
stem length
-is a cross involving a single character flower color
- This involved crossing of two true
breeding parents or pure lines*
with contrasting allele of one
particular trait
monohybrid cross
-is a cross
involving a two character:
Seed color (Yellow /Green)
Seed shape (round/wrinkle
-This involved crossing of two true
breeding parents or pure lines*
with contrasting allele of two
particular traits
dihybrid cross
▪ states that in a heterozygote,
one allele will conceals/hides
the presence of another allele
for the same gene governing a
particular character or
phenotype
▪ The allele that conceals/ hides
the presence of the other allele
is known as dominant allele.
▪ The allele whose presence is
concealed/hidden is known as
recessive allele
law of dominance
During the formation of
gametes, the two alleles of a
gene responsible for a character
separate from each other as
each sister chromatid separates
during Anaphase II
law of segregation
“Genes for the different traits assort
independent of each other during gamete
formation”
law of independent assortment
- A table that shows the genotypes
the two individuals can produce
when crossed - A visual way of representing the
genotypic probability calculations
of offspring in a cross - Limited with working in one or two
gene pairs
Punnett’s Square
invented the Punnett square
Reginald C. Punnett
involves the pattern of inheritance that does not follow Mendel’s laws
non-mendelian genetics
________the traits blend producing an intermediate phenotype.
incomplete dominance
_______ occurs when both alleles are expressed equally in the phenotype of the heterozygote.
codominance
types of codominance
multiple alleles
pleiotropy
lethal alleles
Some populations have multiple alleles of a given gene
multiple alleles
When one gene affects multiple characteristics
pleiotropy
A few genes have alleles that affect the survival of the organisms.
lethal alleles
_______ refers to alleles of a gene having the same phenotypic range
iso-alleles
_______ having the same phenotypic range of an abnormal character
Mutant iso-alleles
________ having the same phenotypic range of an wild type.
Normal iso-alleles
Death occurs in homozygous recessive
individual.
Recessive lethal
Genes whose lethal effect occurs when a dominant allele is present in either homozygote or heterozygote condition.
Dominant lethal
________ lethal genes are expressed in both homozygotes and heterozygotes.
Dominant
are rarely detected due to their rapid elimination from populations.
Dominant lethal genes
death during embryonic development
embryonic lethality
death during fetal development
fetal lethality
death shortly after birth
neonatal fatality
death later in life
adult lethality
are often inherited together into the same gametes
linked genes
Types of Linked Genes
complete linkage
incomplete linkage
These are closely associated linked genes that are always inherited together.
complete linkage
These are distantly associated linked genes that partially segregate from each other during gamete formation.
incomplete linkage
Linkage Notation
Cis form or coupling phase
Trans form or repulsion phase
All dominant alleles (AB) or recessive alleles (ab) are on the same chromatid.
Cis form or coupling phase
Both the dominant allele and recessive allele of linked gene A and B are on the same chromatid.
Trans form or repulsion phase
identifying whether two or more genes are physically link on the same chromosomes. And linked genes tend to be inherited together, making it possible to predict inheritance patterns
Linkage determination
_________ from 1:1 (monohybrid) and 1:1:1:1 (dihybrid) test cross-ratio
deviation
________ from the 9:3:3:1 F2phenotypic ratio
non-conformity
________ is a diagram showing the relative positions of genetic markers along a chromosome that is determined by the recombination frequency during crossover of homologous chromosomes.
linkage or genetic map
________ is based on the crossing over percentage obtained from genetic experiments where 1 map unit is equivalent to 1% crossing over.
map distance
cM
centrimorgan
