Chapter 3 Gen Flashcards
Microscopic examination of chromosomes
provides us with insight to help us understand the inheritance pattern of traits
what are chromosomes made up of biochemically in eukaryotes?
the DNA-protein complex is called chromatin
what is the relationship between chromosomes and genes?
Chromosomes contain the genes
Prokaryotes
Bacteria and archea
Eukaryotes
Protists, fungi, plants, and animals
General features of eukaryotes
Membrane-bound nucleus, mitochondria, lysosomes, and golgi apparatus
Which other organelle contains DNA besides the nuclear genome
The mitochondria contains their own DNA
Cytogenetics
field of genetics that involves the microscopic examination of chromosomes
Roles of a cytogeneticist
examines the chromosomal composition of a particular cell or organism
Two types of cells in animal
Somatic and Germ
Somatic Cells
Body cells, other than gametes
-Blood, nerve, muscle, etc.
Germ Cells
Gametes
-Sperm and egg cells
Karyotype
organized representation (picture) of the chromosomes within a cell
What are the chromosomes in a human karyotype?
46 total chromosomes, 23 per set
Diploid sets of chromosomes
Diploid have all the genetic material the parent cell had so it will have a complete set of chromosomes
Homologous Chromosomes
Two homologs form a homologous pair
Homologous chromosomes extra
-Nearly identical in size
-Same banding pattern and centromere location
-Have the same genes, but not necessarily the same alleles
Locus
physical location of a gene on a chromosome
Are x and y chromosomes homologous to one another?
No, because they differ in size and genetic composition
Cell cycle in eukaryotes
cell division that leads to replication and sorting process
Two major phases of cell cycle in eukaryotes
mitosis and meiosis
What phases happen in interphase?
G1,S,G2
What happens in G1?
In this phase the cell prepares to divide
What happens in S?
Chromosomes are replicated
What happens in G2?
The cell accumulates the materials that are necessary for nuclear and cell division
G0 Phase
A cell in this phase has entered a quiescent state, meaning it has entered a postponed progression through the cell cycle, or it may never divide again
What does the restriction point in G1 determine?
It reaches this point because it is committed to the pathway of cell division
Two major processes of M phase
mitosis and cytokinesis
Difference between homologous chromosomes and sister chromatids
The homolgous chromosomes are the original and the replicate to create the sister chromatids
Dyad
The two sister chromatids are attached together which make them this
Centromere
The place that attaches the sister chromatids together
Kinetochore
This attaches the sister chromatids to the opposite poles which then separate them
chromosome number at the end of G1
46 distinct chromosomes
number after s phase
46 pairs of sister chromatids
What is the relationship/definition of chromosome and chromatid with respect to each
other at different phases G1, G2, early M phase, late M-phase etc?
Purpose of mitosis
To create two identical daughter cells
Prophase
-Nuclear envelope dissociates into small vesicles
-Chromatids condense into more compact structures
-Centrosomes begin to separate
Prometaphase
-Centrosomes move to opposite ends of the cell, forming the
spindle poles
-Spindle fibers interact with the sister chromatids; spindle
apparatus forms
-Kinetochore microtubules grow from the two poles
* If they make contact with a kinetochore, the sister
chromatid is “captured”
* If not, the microtubule depolymerizes and retracts to the
centrosome
-The two kinetochores on a pair of sister chromatids are
attached to kinetochore MT on opposite poles
Metaphase
-Pairs of sister chromatids align themselves along a plane
called the metaphase plate
-Each pair of chromatids (dyad) is attached to both poles by
kinetochore microtubules
Anaphase
-The connection holding the sister chromatids together is
broken
-Each chromatid, now an individual chromosome, is linked to
only one pole
-As anaphase proceeds
* Kinetochore MTs shorten
* Chromosomes move to opposite poles
* Polar MTs lengthen
* Poles themselves move further away from each other
Telophase
-Chromosomes reach their respective poles and decondense
-Nuclear membrane reforms to form two separate nuclei
Look at pictures to identify different parts of mitosis
OK!!!!
