Chapter 4 - Genetics Part I - Heredity and Reproduction Flashcards
asexual reproduction in prokaryotic vs. eukaryotic cells
prokaryotic: binary fission eukaryotic: mitosis
heredity
passing of traits from parents to offspring
gene
a segment of a DNA molecule that codes for a specific trait
Describe the cloning process
- extract mature cell - harvest and enucleate egg - use electrical pulses to combine egg and cell - results in egg cell with donor nucleus that divides and turns into an embryo - embryo is inserted into surrogate organism - surrogate gives birth to clone
Name 3 applications of cloning
agriculture & horticulture; GMOs; saving endangered/extinct species
chiasmata
the site where homologous chromosomes cross and share genetic information
What is the difference between a chromosome and a chromatid?
A chromosome is one “length” or DNA, unduplicated or duplicated; a sister chromatid is what you call each half in a duplicated chromosome
chromatin
thread-like structures within a nucleus; a mass of chromosomes
cloning
the process of producing an individual that is genetically identical to another using one cell
What happens when crossing over occurs?
Segments of homologous chromosomes break and re-attach at similar locations, resulting in new combinations of offspring
Diploid cells contain…
the normal amount of genetic information; 2 sets of chromosomes: one from each parent
Other name for Down syndrome
Trisomy 21
Other name for Edward’s syndrome
Trisomy 18
fertilization
the formation of a zygote by the fusion of 2 gametes
In humans, haploid gametes are called…
ova and sperm
Define gametogenesis and identify 2 processes
Gametogenesis is the process in which cells undergo meiosis to produce gametes; oogenesis in female ovaries and spermatogenesis in male testes
How many viable cells can oogenesis and spermatogenesis produce?
oogenesis - 1 viable cell and 3 polar bodies spermatogenesis - 4 viable cells
homologous chromosomes
matching pairs of chromosomes that are similar in size and carry info for the same genes; just different versions of each other
What do you call the location of a gene on a chromosome?
The location of the gene is referred to as the locus (s.) or loci (pl.)
karyokinesis
the division of a cell nucleus during mitosis
Describe interphase
duplication of chromosomes
Describe the stages of mitosis.
Prophase - chromosomes shorten and thicken, nuclear membrane dissolves, and centrioles (small protein bodies) form spindle fibres
Metaphase - chromosomes align along the equator
Anaphase - centromeres divide and chromatids move to opposite ends of the cell
Telophase - chromosomes reach the poles and begin to unwind, spindle fibres dissolve, nuclear membrane forms
*cytokinesis is technically not part of mitosis - it is the second stage of cell division
Describe Meiosis I.
Prophase I - nuclear membrane dissolves, centrioles form spindle fibres, chromosomes shorten & thicken, homologous chromosomes form tetrads, synapsis
Metaphase I - homologous chromosomes line up at equator, align centromeres across middle of cell
Anaphase I - one chromosome from each homologous pair moves to opposite poles; centromeres do not split
**Telophase I **- nuclear membrane forms, sometimes cytokinesis occurs, unlike mitosis chromosomes in each nuclei are not identical
*cells are now haploid
What is a tetrad?
a pair of homologous chromosomes, each with 2 sister chromatids
What is synapsis?
when chomatids intertwine with a matching chromatid during prophase I of meiosis
Describe Meiosis II
* between meiosis I & II, DNA not duplicated and there is no interphase
**Prophase II **- chromosomes shorten & thicken, nuclear membrane dissolves, spindle fibres forms
Metaphase II - chromosomes (each with 2 sister chromatids) line up at equitorial plate, remaining attached at centromere
Anaphase II - sister chromatids separate and move to opposite ends of the cell
**Telophase II **- nuclear membrane reappears, division of cytoplasm follows
* results in 4 sex cells that are all genetically different
What are sex chromosomes referring to?
Sex chromosomes are referring to the X and Y chromosomes; their combinations determine the sex ( 2X, 0Y = female; 1X, 1Y = male)
What are somatic cells?
Body cells - any cell that is not a reproductive cell
What are karyotypes?
visual arrangements of chromosomes; sorted based of size and shape
In the human body, how many chromosomes do somatic cells and gametes have?
All somatic cells have 46 chromosomes (23 homologous pairs), which is the diploid number.
Gametes (sex cells) have 23 chromosomes, which is the haploid number.
Turner’s syndrome
1 X and no Y chromosome
Klinefelter syndrome
2 X and 1 Y chromosome
Difference between a trisomy and a monosomy
In place of a homologous pair, a trisomy contains 3 chromosomes, and a monosomy contains only 1 chromosome
What is non-disjunction?
failure of homologous pair of chromosomes to move to opposite poles during meiosis
What is the sequence of a cell cycle?
G1 - S - G2 - mitosis - cytokinesis
How does meiosis result in genetic variability?
- Unique haploid cells meet with other unique haploid cells at fertilization
- When crossing over occurs, genetic info. is swapped
