Module 4: DNA Flashcards
Conserves number of chromosomes sets, producing cells that are genetically identical to the parent cell
Mitosis
Reduces number of chromosomes sets from 2n to n producing cells that differ from each other and from the parent cell
Meiosis
The exchange of genetic information between the pair of homologous chromosomes allows genetic variation among the population.
Creates Genetic Diversity
Recombination through meiosis can replace
that abnormality in the next generation,
allowing the formation of a healthy individual.
Repairs Genetic Defects
When the chromosomal reduction process is not maintained it causes what?
Genetic Abnormality
Further coil and condense or gather to form fibrous material which is called Chromatin
Nucleosomes
Are thread-like structures in which DNA is tightly packaged within the nucleus
Chromosomes
DNA Molecules first wrapped around the histone proteins forming beads on string structure called what?
Nucleosomes
The number of A and T bases are equal and the number of G and C bases are equal, what rule is this?
Chargaff’s rule
A polymer of nucleotides, each consisting of a nitrogenous base, a sugar, and phosphate group.
Deoxyribonucleic acid or DNA
In 1953, two people introduced a double-helical model structure base on Rosalind Franklin’s X-ray crystallography the DNA molecule.
James Watson and Francis Crick
A is paired to T. What do you call A and T?
Adenine & Thymine
G is paired to C. What do you call G and C?
Guanine & Cytosine
The parent molecules unwind and make what?
Two new daughter strands.
Watson’s and Crick’s semiconservative model of replication predicts when a double helix replicates, each daughter cell will _____ and one ______
one old strand (conserved); newly made strand
Three types of DNA replication
Initiation, Elongation, Termination
What do you call when two DNA strands are separated opening up a replication “bubble”
Origins of replication
A eukaryotic chromosome may have ____ of origins of replication.
Hundreds or even thousands
Replication proceeds in _____ from each origin until the either molecule is copied.
Both directions
It is a Y-shape region at the end of each replication bubble where new DNA strands are elongating.
Replication Fork
Enzymes that untwist the double helix at the replication forks.
Helicases
To bind to and stabilize single stranded DNA (Keep the strand separated)
Single-strand binding proteins
Corrects “Overwinding” or “Supercoiling” ahead of replication forks by breaking, swiveling and rejoining DNA strands = UNTANGLES
Topoisomerase
Enzyme that adds RNA bases in the strand which creates the RNA primer.
Primase
Initiates synthesis of DNA polynucleotide
RNA Primer
Binds to RNA primer and adds DNA bases (free nucleotides)
DNA Polymerase 3
The antiparallel structure of the double helix affects what replication?
Antiparallel Elongation
A new DNA strand cna elongate to only in the ____ to ___ direction
5’ to 3’
Synthesized continuously in the 5’ to 3’ direction towards the replication fork.
Leading Strand
Synthesized discontinuously in short segments because DNA polymerase can only add nucleotides in the 5’ to 3’ direction, but this strand runs in the 3’ to 5’ direction relative to the replication
Lagging strand
Removes RNA primer which initiated the replication and replaces them with DNA Nucleotides
DNA Polymerase 1
Joins Okazaki Fragments
DNA Ligase
Removal of Helicase
Ubiquitin Ligase Complex
Replication continues until the ___________
The entire DNA molecule has been duplicated
In _____,Termination occurs when the replication forks meet.
In ______, multiple replication forks eventually merge.
The process where parent cell divides into two or more daughter cells.
Cell Division
Two main types of cell division.
Mitosis and Meiosis
By ________, cells ensure that genetic information is accurately transmitted, maintaining the organism’s integrity and function.
Replicating DNA before cell division
_______, depend on cell division for development from a fertilized cell, growth, repair.
Multicellular eukaryotes
In _______, division of one cell reproduces the entire organism.
Unicellular organisms
Is the transmission of traits from one
generation to the next
Heredity
Is demonstrated by the differences in
appearance that offspring show from parents
and siblings
Variation
Is the scientific study of heredity and
variation
Genetics
An ordered display of the pairs of
chromosomes from a cell
Karyotype
Human somatic cells have _____
of chromosomes
23 pairs
the two chromosomes
in each pair
Homologous chromosomes or homologs
homologous pair of X
chromosomes (XX)
Human females
one X and one Y
Human males
The remaining 22
pairs of chromosomes.
Autosomes
Determine the sex of the
individual
Sex chromosomes
A ______ (2n) has two sets of chromosomes. For humans, 46 (2n = 46)
Diploid cell
A _______ contains a single set of
chromosomes and is haploid (n).
For humans, 23 (n = 23)
gamete (sperm or egg)
Two copies of each chromosome
Diploid
One copy of each chromosome
Haploid
the union of gametes (the sperm and the egg)
Fertilization
- The fertilized egg
- has one set of chromosomes from each parent
- produces somatic cells by mitosis and
develops into an adult
Zygote
is a cell division process where
a single (parent) cell divides twice to
produce four independent (daughter)
cells, each having half the
chromosomes as the original cell.
Meiosis
Meiosis takes place only in the ______.
reproductive cell types
For a cell to undergo meiosis, it must
have a ______ chromosome
number.
diploid (2n) chromosome
- Preparatory phase of
cell division - Each chromosome
duplicates to become
two identical sister
chromatids. - The centrioles get
duplicated as well.
Interphase of Meiosis
- Spindle fiber attached to centromere
- Homologous pairs of chromosomes align along the center of the cell
Metaphase I of Meiosis
The tetrads are separated and chromosomes with
two sister chromatids (homologous) migrates to the
opposite poles.
Anaphase I of Meiosis
*The chromosomes
stop migrating with
each pole.
*The nuclear
envelope
reappears, and the
spindle fibers
disappear.
*Contains a haploid
number of
chromosomes.
Telophase I of Meiosis
*The chromosomes
uncoil and become less
dense.
* Nucleolus reappears
within the nucleus.
*Two different daughter
cells are formed, each
with half the number of
chromosomes as the
parent cell.
Cytokinesis I of Meiosis
