Module 1 Flashcards
gene
a specific segment of DNA in a discrete region of a chromosome that serves as a unit of function by encoding a particular RNA or protein.
darwin published his findings in
on the origin of the species
what did darwin study
alternative traits in pea plants
where was mendel based in
austria
gregor mendel was a
monk
why were the peas a good model
peas are self fertilizing
they can be crossed fertilized
peas allow for pure bred lines
havge discrete alternative traits
cross fertalized
pollen from one flower can be put onto female flower
F1 means
first filial
F2 means
second filial
pea experiment describe it
he had 2 pure colored peas and mixed them together. they all came out to be yellow. however, the next generation after that was mixed with more yellow but some green.
gregor mendels results said
a trait must have 2 forms (dominant and recessive)
alternative forms pf tje traits are called alleles.
for each trait a individual carries 2 alleles one from mother and father
Punnet square used to visualize a
cross
who made punnet squares
reginald punnet, did it with chickens
Mendels first law of segregation
the two alleles of each trait separate during gamete formation and then unite at random one from each parent at fertilization.
what allele is seen in f1 generation
Dominant
test cross
crossing organism with genotype you dont know. and with genotype you do know.
mendels laws typically apply to
diploids
in mendels first law an allele passed from parents to is
random
mendels dihybrid cross
used to determine multiple traits of an organism. such as green and wrinkled.
law of independent assortment
crossing heterozygous individuals for 2 traits gives a ratio of
9:3:3:1
crossing heterozygous individuals for 2 traits gives a ratio of 9:3:3:1 but the color ratio and wrinkled ratio seperatley are still
3:1
crossing heterozygous individuals for 2 traits would give a 9/16 and 1/16 in F2 generation. and recombinent phenoyupes of 3/16 and 3/16. mendel explained this as
two traits being followed in the dihybrid cross must be inherited independently meaning they were not linked.
mendels law of independent assortment
during gamete formation different pairs seperate independelty of each other. this means getting a specific trait diesbt influence which trait you get for a different gene.
law of independent assortment occurs in metaphase 1 of
meiosis
inheritence is particulate not
blending
blending
offspring inherit trauts as a simple blend of their parents characteristics. like mixing paint
gamate contain ___ form of each trait
one
forms segregate
randomly
different traits assort ___
independetly. wrinkeld was independent of color
what makes a dominant and recessive allele. example:
R has an enzyme that can convert un branched starch to branched starch making it round. and small r doesnt have that enzyme so it remains unbranchjed making it wrinkled.
staining cells allow for
better visualization
who used staining to see thread like structures in cell division
walter flemming
what shape is chromosome
X
what is center of chromosp,e called
centromere
what are sister chromatids
the lower parts of the X
If x is rather even it is a ____ chromosome
metacentric
if x is lopsided it is a ____- chromosome
acrocentric
non sister chromatids are
create similar but not identical homologous chromosomes
sister chromatids create
identical copies of chromosome
mitosis occurs in ___ cells
somatic
has 2 daughter cells that contain same number of chromosomes as parennt
mitosis
what type of cell division creates daughter cells that contain half the number of chromosomes as the parent cell contains
meiosis
meiosis occurs in
germ cells.
where do germ cells that do meiosis are
tests and ovaries
purpose of meiosis is to make cells that are
involved in sexual reproduction
in meiosis one cell divolves into
4 daughter cells (sperm and eggs)
single chromosome set known as
haploid or n
mitosis results in ____ cells
somatic
gametes have a ____ chromosome set
single
mitosis makes 2 matching sets or
diploid/ 2n
in humans the diploid number is
46
human haploid number is
23
meiosis reduces the number of chromosomes in reproductive cells from ___ to __
2n to n
how many rounds of dna replication does meiosis have
1
how many types of cell division are there
- (meiosis and mitosis)
how many cell divisions is in meiosis
- meiosis I and II
prior to meiosis I what occurs
dna replication
In meiosis I ____ seperate
pairs of chromosomes
in meiosis II____ seperates
sister chromatids
each meiosis phase has how many phases
- PMAT
how many phases are in Prophase
5
prophase phases in order
Leptotene, zygotene, pachytene, diplotene, diakinesis
Leptotene
centromeres begin to move towards opposite poles, and chromosomes thicken
zygotene
homologous chromosomes come together to undergo synapsis
pachytene
synapsis is complete, crossing over occurs
crossing over.
genetic exchange between non sister chromatids and homologous pairs
diplotene
the synaptonemal complex dissolves, and homologous chromosomes separate from each other, except at the crossing over sites. These sites are called chiasmata, and X-shaped compositions form.
Diakinesis
diakinesis
The chiasmata terminalize, and the meiotic spindle assembles. The nucleolus disappears, and the nuclear envelope dissociates. Chromosomes reach their maximum coiling and shortening at this stag
meiosis I metaphase I
homologous chromosomes line up as pairs along metaphase plate or equator of cell. spindle fibers attach to chromosome
meiosis I anaphase I
homologous chromosome pairs pulled to opposite pars, and sister chromatids satay together.
Meiosis I telophase I
nuclear envelope reforms. cells have half the number of chromsomes
interkinesis
period between meiosis I and II. no chromosomal duplication
Meiosis II Prophase II
chromatids become thicker and shorter. nuclear membrane dissapears. spindle fibers reassemble
meiosis II metaphase II
chromosomes aling along with metaphase plate and spindle fibers attach to chromsomes
Meiosis II Anaphase II
sister chromatids move to opposite poles
Meiosis II Telophase II
chromosomes uncoil and go back to normal bout it has a reduced chromosome number. nuclear membrane reforms
Prophase I again
crossing over takes place
crossing over process cartoony explanation
2 X’s and you cut off an arm on each and stick it on other
after meiosis
gametes are ready for fertizilation
fertilization gives you a
zygote
fertilization restores
diploid number of chromosomes
human karyotype all chromosomes explained
1-22 chromosomes known as autosomes and last X and Y are sex chromosomes
boveri and sutton proposed _____
chromosome theory
chromsome theory
proposes that chromsomes bear hereditary factors in
accordance with Mendelian laws
in chromosome theory each cell contains ___ copies of each chromosome
2
mendels proposal each cell contains ___ copies of each gene
2
chromosome theory- transmission
chromosomes dont change with transmission
Mendel’s proposal- transmission
genes dont change with transmission
mendels theory- allele
alternative alles segregare to different gamatres (law of segregation)
chromosome theory
homologous chromosome pair and then seperate to different gametes (metaphase and anaphase I)
chromosome theory- assortment
Maternal and paternal copies of
chromosome pairs separate without regard to the assortment
of other homologous chromosome pairs
mendel theory- assortment
Alternative alleles of unrelated genes assort independently
(Law of Independent Assortment)
chromosome theory- alleles unite randomly
At fertilization, an egg’s set of
chromosomes unite with randomly encountered sperm’s
chromosomes
mendels theory of alleles
alleles obtained from one parent unite at random
with those from another parent
chromosome theory fertelized egg
In all cells derived from a fertilized
egg, one chromosomes in a pair is of maternal origin, and the
other chromosome in the pair is of paternal origin
mendels theory- fertilized egg
In all cells derived from a fertilized gamete, one half
of genes are of maternal origin, and half are paternal.
Genetic diversity due to meiosis occurs in 2 ways
independent assortment of non homologous chromosomes and crossing over between homologous chromosomes
independent assortment of non homologous chromosomes
different combinations of alleles aong chromosoems
crossing over between homologous chromosome
different combinations of alleles within each chromosome
independent assort takes place in
metaphase I along metephase plate
walter sutton studied
great lubber grasshopper
walter sutton after studying grasshoppers discovered
after fertilization grasshoppers with XY were males and XX were females
who determines gender in child
father
what chromosome will females give
1-22 autosomes and one X
what chromosomes will males give
1-22 autosomes and an X or a Y
chromosome theory prediciton
if genes are on specific chromosomes, then
traits determined by a certain gene should be transmitted
with the chromosome
thomas hunt morgan used what for his testing
drosophila, fruit fly
why did thomas hunt use drosophila
eye color, easy to tell male and female
why was there a white eye in fruit fly
mutation
a mutation in allels would b represented like
w^+w or ww
thomas hunt after finding white eye ran test crosses and end found that all red means
white eye is recessive trait
in thomas hunts next gebneration he crosses 2 heterozygous and found all white eyes were
Male
in thomas hunts third cross he got ratio of
1:1 ratio with males and females
in thomas hunts 4th cross he got
1:1 ratio but alll males had white eyes again
thomas hunts last cross was a ____
reciprocal cross
reciprocal cross
a breeding experiment that involves crossing two organisms twice, switching the sexes of the parents in the second cross
Thomas Hunt found that gender based eye color could only be explained if
eye color gene was x linked. transmitted on x chromosome
females in thomas stock of flies could still show white eye color if
they had 2 recessive alleles
males in thomas hunts stock of flies would show white eyes if
they only had one allele for it. since they only have one X chromosome.
the males in thomas hunts experiment are said to be _____ for eye color
hemizygous
hemizygous
having only one copy of a gene or chromosome segment instead of the usual two
wild type allele
allele that is found in high frequency in a population.
wild type allele is denoted with
+, it is common
mutant alleles are ____ frequency
low
how are mutant alleles denoted
no symbol
dominant mutation written as
gene symbol is upper case
recessive mutation is written as
lower case gene symbole
hemophilia is
x linked recessive
Explain the correlation between Mendel’s two laws and the process of meiosis
directly correlate with the physical processes that occur during meiosis, specifically the separation of homologous chromosomes during Meiosis I (Segregation) and the random alignment of these chromosomes at the metaphase plate during Meiosis I (Independent Assortment)
Explain the chromosomal theory of inheritance
genes are located on chromosomes, and the behavior of chromosomes during meiosis explains how traits are inherited according to Mendel’s laws;
Correlate Mendel’s laws with the chromosomal theory of inheritance
he chromosomal theory of inheritance directly explains Mendel’s laws, stating that chromosomes, which separate during meiosis, are the carriers of genes, thus providing a physical mechanism for the segregation and independent assortment of alleles observed by Mendel; essentially, the behavior of chromosomes during meiosis perfectly aligns with the patterns of inheritance described by Mendel’s laws
