prelims 25% Flashcards
Branch of genetics that is concerned with how
chromosomes behave
cytogenetics
● Provides information on the structures and
numbers of chromosomes
● Determine abnormalities in chromosomes and
associate them with diseases
cytogenetics
● A rare genetic disorder due to the partial loss
or deletion of chromosome 5
● French term - “cat cry
what syndrome is this
CRI DU CHAT SYNDROME
→ Found in the nucleus and mitochondria(Eukaryotic)
→ Encodes genetic makeup of most organisms
→ Central molecule of
DEOXYRIBONUCLEIC ACID
DNA
→ Also called DNA synthesis
→ Process of duplicating DNA during cell division
dna replication
→ DNA replication that occurs in vitro (outside the cell)
→ May be made in the laboratory
→ Amplify specific gene of interest
polymerase chain reaction
→ Copies the entire genome (whole DNA or genetic makeup) of a cell from one end to another
cellular DNA REPLICATION
A process in which the Genetic information carried by DNA transcribed
into RNA
transcription
● Information carried by the transcribed RNA
(mRNA) is translated to protein
● Carries out work to sustain life
translation
DNA replication occurs during ?
cell division
DNA replication occurs during the _ phase of
the cell cycle
s phase
A replication model which produces 2 DNA helices
in which each strand
contains alternating segments of old and new
DNA
dispersive
Produces 2 DNA helices in which 1 helix contains
entirely new DNA
(kind of replication model)
conservative
A replication model which Produces 2 DNA helices
in which each helix contains 1 new strand
and 1 old strand
semi conservative
Consists of polymer of deoxyribonucleotides
units
dna structure
purine or pyrimidine covalently
bonded to a sugar molecule
nucleoside
Sugars are bonded to nitrogenous bases by
_________ bonds
glycosidic bondz
Complementary base pairing occurs by
_________ bonding
hydrogen bonding
→ Independent replication of each parental strand, so that the resulting DNA molecules each contain 1 parental strand and 1 newly synthesized daughter strand
dna replication is semiconservative
→ Replication in eukaryotes start at any point along the linear DNA double helix, which are called origin of replication
bidirectional
Short fragments are called
Okazaki fragments
→ Recognize RNA primer
→ Starts extending the primer by adding in DNTPs (deoxyribonucleotide triphosphates
dna polymerase
this strand goes Away from the replication fork
lagging strand
- For prokaryotes, elongation is performed by
dna polymerase III
Displacement of RNA primer is facilitated by this enzyme
FEN1 (Flat endonuclease 1)
→ Seals the nick between adjacent Okazaki fragments
* For prokaryotes, it is performed by DNA Pol I
dna ligase
→ Starts to cut DNA and unwind to relieve the tension produced by opening up the replication fork
topoisomerase II
it chews up RNA primers to get rid of them
RNAse
it facilitates formation of
phosphodiester between nucleotides (acts as a gap sealer between Okazaki fragments
dna ligase
This Occurs in the nucleus and consists of 3 stages:
➢ Initiation ➢ Elongation ➢ Termination
EUKARYOTIC TRANSCRIPTION
what stage of eukaryotic transcription is this:
RNA polymerase has to bind with DNA
at the promoter region -RNA polymerase needs help from
various enzymes to locate the promoter region
initiation
Directionality of RNA Polymerase
5’ to 3’
formation of hairpin loop is an example of
prokaryotes termination
→ 15% of total cellular RNA
carry amino acid to ribosomes, serve as adapters
tRNA
5% of total cellular RNA
Function: direct carrier of genetic information from genes to ribosomes for protein synthesis
Types: heterogenous in length, spectrum variable
Features: short lived
mRNA
RNA POL II AND III is located in??
nucleoplasm
→ Catalyzes synthesis of small RNA and small subunits of rRNA, small cytoplasmic RNAs
RNA POL III
located in the nucleus
→ Catalyze the synthesis of large subunits of rRNA
RNA POL I
synthesis of mRNA from DNA
transcription
synthesis of proteins from RNA
translation
Addition of _______________
→ Protects transcript from degradation → Helps transcript get recognized by the ribosome
→ Occurs in the nucleus
5’ guanosine cap
Addition of ?
→ Modified Adenines → Occurs in the nucleus
poly A tail
● Made of ribosomal RNA
● Large and small subunit
● Abundant in eukaryotic cells
ribosomes
→ How do ribosomes recognize mRNA? (pro)
shine dalgarno sequence
→ How do ribosomes recognize mRNA? eu
Kozak sequence
_____ sequence
-More complex -Ribosome recognizes the 5’ guanosine
cap -First AUG is start codon
Kozak sequence
Translation is terminated when the ribosome
encounters a ?
stop codon
Gametes unite at random and irrespective of the other gene pairs involved. this is a Law of ?
law of independent assortment
introduced a new theory of inheritance based on his experimental work with pea plants
Gregor Mendel
Traits are always controlled by
single genes
observable physical traits
phenotype
different forms of genes (symbolized by
a letter) (uppercase - dominant; lowercase - recessive
alleles
combination of alleles of all genes
genotype
specific location of genes in
chromosomes
locus
Crosses of parent organism that differ
only by 1 trait (one plant seed or seed characteristic)
-E.g: seed colors
monohybrid cross
Allows calculation of frequency of the type of
offspring
punnett square
Genes independently assort at a distance of __
cM (centimorgan) or more apart
50cM
-Involves two characters: parents posses 2
different forms of each character -E.g: yellow, round x green, wrinkled peas -RRYY x rryy
-Homozygous dominant x homozygous recessive
dihybrid cross
Law of __________:
● Alleles at the same locus on pairs of
chromosomes separate
● Each offspring has the same chance inheriting a
particular allele from a parent
segregation
Law of _______________
● Every offspring has the same chance to inherit
any allele at any other locus
● Has a few exemptions
Law of Independent Assortment:
Alternative traits, such as tall and short, are
determined by hereditary “factors.” These determinants are called
genes
basic unit of the chromosome
nucleosome
systematic visual representation of
a karyotype
karyogam
thickened and deeply stained during Interphase, corresponds to regions with inactive genes
heterochromatin
less densely stained and are usually invisible during cell division and Interphase, corresponds to regions with active genes
euchromatin
telomere is positioned sa center,
chromosomes appear to be s shaped
metacentric
centromere is positioned near
the middle, one chromosome arm is shorter than the other (obvious P and Q arms
submetacentric
appears as chromosome with long
arm only, no short arm
telocentric
A gene recessive in females will be expressed in
male offspring. True or False
tru
one type of cell have several cell population that each expresses a specific characteristic
mosaicism
split of daughter cells
mitosis
division of cytoplasm &
formation of 2 daughter cells
cytokinesis
the process by which
prokaryotic cells divide
binary fission
Produces 2 daughter cells, identical to parent
cells
mitosis
the sequence of events that
occur in a cell between its formation and its division into two daughter cells
cell cycle
cell cycle is divided into two main phases
interphase and mitosis
● The longest stage of the cell cycle
● Divided into three phases: G1, S, and G2
● During this stage, the cell grows and carries
out its normal functions
interphase
● Chromatids condense becoming
chromosomes
● Centrioles separate and start moving to
opposite ends of the cell
● Spindle begins to form
what stage of cell cycle is this
early prophase
● The nuclear membrane fragments and the
microtubules invade the nuclear area
● Centrioles have moved to the opposite lanes
● Sister chromatids are formed with a centromere
late prophase
● The paired chromosome separate and move to
the opposite pole
● The spindle apparatus shortens and chromatids
are pulled apart
● Partial division of cytoplasm begins
anaphase
● Spindle fiber disappear
● Chromosomes arrive at the opposite end of the
cell and begin to relax
● Centrioles are replicated
● Nuclear membrane reform and nucleoli
reappear
telophase
● Occurs at the end of mitosis
● Daughter cells are genetically identical
● Cell turns to interphase
● Microtubules help organelles and cytoplasm
divide
cytokinesis
what checkpoint decides whether or not the cell
will divide
g1 checkpoint
what checkpoint determines if DNA has been
properly replicated
g2
-Cyclin dependent kinases, phosphorylates
cellular proteins -regulatory proteins, levels cycle in the cell
protein kinase
Triggers passage through different stages of cell
cycle -Phosphorylation
Cdk-cyclin complex
programmed cell death
that is essential for normal development and functioning of multicellular organisms
apoptosis
divides by mitosis
○ Produces two daughter cells or a stem
cell and a progenitor cell, which may be partially specialized
○ Progenitor cells do not have the
capacity of self-renewal
stem cell
● Centrioles move to opposite ends
● Chromosome become visible
● Spindle apparatus form
● Nuclear membrane and nucleolus disappear
● Substages: leptotene, zygotene, pachytene,
diplotene and diakinesis
meiosis prophase I
● Homologs align down at the center of the cell
● Homologous pair attaches to the spindle fiber at
an opposite pole
● This alignment results in temporary fusion of the
chromatids that results in crossing over that mixes parental traits
metaphase I
● Spindle fibers contracts pulling the 2
homologous chromosomes of each bivalent toward the opposite poles of the cell
● Centromeres of each chromosome do not divide
anaphase I
● Nuclear envelopes partially assemble around
chromosomes
● Spindle disappears
● Cytokinesis divides cells into two
telophase I
● The spindle fiber attaches to the kinetochore of
each chromosome and aligns the chromosomes at the equatorial plate
● Half the number of chromosomes is because of
chromosome reduction in Meiosis I
metaphase II
● Spindle fibers retract
● Centromeres divide and each of the 2 sister
chromatids is drawn to the opposite poles
● Chromatids are not identical unlike mitosis
anaphase II
● Cleavage furrows appears
● Division of cytoplasm
● Formation of nuclear envelope
● Spindle fibers disappear
● Chromosome decondense
telophase II
● Form four genetically different cells
● Each with half the number of original
chromosomes (haploid
cytokinesis II
● Is the process of production of haploid sex cells
● Gametes have one-half the genetic material
(haploid chromosome number) from the germ cell of each parent
gametogenesis
● Fusion of spermatozoa and ova at time of
fertilization results in a ________ with diploid genome
zygote
The process of production of spermatozoa is
called
spermatogenesis
the process of production of the oovum is
oogenesis
In females, oogenesis (meiosis 1) starts at
__________ stage
embryonic
