Bio chap 4 Flashcards
What is Genetics?
It’s a field in biology where they study how genetic information is passed from one generation of organisms/cells to the next.
What is the full name of DNA?
Deoxyribonucleic Acid
What is DNA?
Genetic information that an individual inherits from his/her parents.
What are the nucleotides in DNA?
- A sugar (deoxyribose)
- A phosphate group
- A base
What are the 4 bases of DNA? Which pairs with which and how many H-bonds are formed?
A - adenine
T - thymine
G - guanine
C - cytosine
A and T with 2 H-bonds
C and G with 3 H-bonds
What is the orginization of eukaryotic chromosomes in order?
- DNA double helix
- DNA wrapped around histone
- Nucleosomes coiled into a chromatin fibre
- Further condensation of chromosome
- Duplication of chromosome
True or False:
There is a relationship between the amount of chromosomes an organism has and it’s complexity.
False
What is a Gamete?
A specialized reproductive cell, either an egg or a sperm. (haploid)
What is a Somatic cell?
A plant/animal body cell
What is the chromatin definition?
A relaxed form of DNA.
What is the definition of chromatids?
A duplication of a chromosome.
Sperm and ovum are _______ (haploid/diploid) cells.
Haploid
Fertilization is a _______ (haploid/diploid) cell.
Diploid
What is the definition of allele?
One of two or more versions of DNA sequence at a given genomic location.
True or False:
22 out of the 23 pairs of chromosomes are homologous.
True
What are autosomes?
True homologous pairs.
Why is the X chromosome bigger than the Y chromosome?
Because it has more genes.
What is a karyotype?
A person’s set of chromosomes.
How are karyptypes made?
A karyotype analysis usually involves blocking cells in mitosis and staining the condensed chromosomes with Giemsa dye. The dye stains regions of chromosomes that are rich in the base pairs Adenine (A) and Thymine (T) producing a dark band.
How are chromosome pairs arranged on karyotypes?
In order of their length, from longest to shortest. The sex chromosomes are organized last.
What are the 3 parts of the cell theory?
- All living things are composed of one or more cells.
- Cells are the smallest unit of living organisms.
- New cells come only from re-existing cells by cell division.
The cell cycle duration depends on …
- The cell type
- The organism
What are the 3 functions of the cell cycle?
- Growth of the organism
- Repair tissues and organs
- Maintenance to replace dead cells
Specific checkpoints:
- Monitor growth
- Ensure the cycle continues or stops appropriatley
What is regulation?
It is the key to preventing uncontrolled and rapid growth.
What are the 3 main stages of Mitosis? Give a short summary of each.
- interphase: growth and intese cell activity
- Mitosis: nucleus and genetic material divide
- Cytokinesis: division of the cell cytoplasm and creation of new cells
How many phases of interphase are there? Give a short summary of each.
- Growth 1 (G-1): major period of growth
- Synthesis (S): DNA (also called chromatin) is replicated
- Growth 2 (G-2): further growth and molecule synthesis
When does DNA replication happen and how does it happen?
It happens during Interphase.
- Double helix unwinds
- Each strand of DNA serves as a template
- Each new double helix contains one original strand and one new strand
What is a chromosome?
A structure in the nucleus that contains DNA.
What is a sister chromatid?
One of two chromosomes that are genetically identical and held together at the centromere.
What is a centromere?
The region where two sister chromatids are held together in a chromosome.
What are the 4 phases of Mitosis?
- Prophase
- Metaphase
- Anaphase
- Telophase
What are the main things that happen in Prophase?
- Nuclear membrane breaks down
- Chromatin condenses into chromosomes
- Chromosomes become visible under a microscope
- Sisiter chromatids are joined together at the centromere
- Centrosomes release spindle fibres
What is a centrosome?
A structore that helps form spindle fibres.
What are spindle fibres?
Microtube structures that facilitate the movement of chromosomes within a cell.
What are the main steps of Metaphase?
- Spindle fibres attach to the centromeres of sister chromatids
- Spindle fibres guide the chromosomes to line up at the equator of the cell
What are the main steps of Anaphase?
- Each centromere splits apart
- Sister chromatids seperate from eachother
- Sindle fibres contract and shoretn while pulling the chromosomes to opposite poes of the cell
What are the main steps of Telophase?
- Chromosomes unwind into chromatin
- Spindle fibres break down
- Nuclear membrane forms around the new set of chromosomes
- Two daughter nuclei are formed
What are the different cell types in cytokinesis?
Animal cells and Plant cells
What are three facts about animal cells during cytokinesis?
- microfilaments constrict
- furrow in cell mebrane along the equator of the cell
- Deepens and pinches off into two cells
What are three facts about plant cells during cytokinesis?
- Rigid cell wall does not pinch inward
- A cell plate forms between the daughter nuclei
- A cell wall forms on each side of the cell plate
What are Prokaryotic cells?
Cells with no nucleus that have gone through complete cell division with binary fision.
How can you obtain genetic variation during asexual reproduction?
DNA mutation.
What is sexual reproduction?
The fusion of two gamete cells which results in an offspring with a lot of genetic variation from the parents.
How are gametes created?
Through meiosis.
What is binary fission?
A single parent cell divides into 2 daughter cells (asexual)
What is budding?
Parent cell produces bud, it gets detached and develops into a new individual (asexual)
What is spore formation?
Reprouces by forming spores undrer favourable conditions. Spores develop into new individuals (asexual)
What is fragmentation?
Organism with filamentous body breaks into 2 or more fragments. Each fragment grows into a new individual (asexual)
What is regeneration?
Organism regrows a lost limb or another part of the body. (asexual)
What is vegetative reproduction?
Organism produces new individuals by a vegetative part of the plant (asexual)
What is fertilization?
Fusion of a male reproductive cell with a female reproductive cell.
Egg + Sperm = ?
Zygote
What are the two genetic outcomes for Meiosis?
- Genetic reduction: produces daughter cells with half the # of chromosomes of the parent cell.
- Genetic recombination: the produts of meiosis have different combinations of alleles.
Explain Prophase 1.
- Centrosomes move to the poles of the cell and spindle apparatus forms
- Homologous chromosomes line up side-by-side in an alignment called synapsis.
- Crossing over
What is crossing over?
When genetic material between maternal and paternal chromosomes is exchanged.
Explain Metaphase 1.
- Spindle fibres attach to the centromeres of each homologous chromosome.
- Homologous chomosomes are lined up together along the equator.
Explain Anaphase 1.
- The microtubules in the spindle fibres contract and shorted.
- Homologous chromosomes are seperated.
- Sister chromatids remain attached.
- The chromosome # has been reduced to haploid n = 23.
Explain Telophase 1.
Homologous chromosomes uncoil and sindle fibres disappear.
Explain Cytokinesis (Meiosis 1).
- A nuclear membrane forms around each group of chromosomes.
- Two haploid daughter cells.
Explain Prophase 2.
- Both haploid daughter cells undergo the same process.
- Similar to mitosis.
- Chromatin coils to form chromosomes.
- Nuclear membrane disappears
- Splindle fibres begin to form.
Explain Metaphase 2.
- Similar to mitosis.
- Spindle fibres attach to the centromeres of each sister chromatid.
- Sister chromatids line up at the equator of the cell.
Explain Anaphase 2.
- Spindle fibres contracct and shorten.
- Sister chromatids are seperated and pulled to opposite poles of the cell.
- Both sides of the cell remain in a haploid state.
Explain Telophase 2 and Cytokinesis.
- Both haploid cells undergo telophase and cytokinesis.
- Forms a total of 4 haploid cells.
- A nuclear envelope forms around each nucleus.
- Spindle fibres disappear.
- Each haploid cell is genetically different from the others.
What is spermatogenesis?
The process that produces sperm in male animals.
Starting at puberty the ______________ reproduce by mitosis and then meiosis.
spermatogonia
What is oogenesis?
Produces eggs in females.
The _______ reproduce by mitosis before birth, begin meiosis and stop at _______ _.
oogonia, prophase 1
True or False:
During oogenesis, the cytoplasm is equally distibuted, and all the cells mature.
False
What is Genetic Variation?
The difference in DNA sequences between individuals within a population.
Genetic Variatioin happens in gamete cells through:
- Independent Assortment
- Crossing Over
- Random Fertilization
What happens during Independent Assortment?
- During metaphase 1, each homologous chromosome is randomly oriented towards one of the poles.
- For each pair of homologous chromosomes, there is a 50/50 chance that a daughter cell will get the maternal or paternal chromosome.
What happens during Crossing Over?
- During prophase 1, non-sister chromatids exchange genetic material in multiple sections.
- Produces new combinations of matgernal and paternal genes (recombinant chromatids)
- It is a random process and contributes to genetic diversity in the population.
What is Random Fertilization?
The fusion of two gametes will produce a zygote with any of the 70 trillion diploid combinations.
What are the two major types of errors in meiosis?
- Errors in chromosome number.
- Errors in chromosome structure.
What are errors in chromosome # caused by?
Non-disjunction
- Homologous chromosomes do not seperate properly during meiosis 1.
- Sister chromtids do not seperate during meiosis 2.
What does monosomic mean?
Missing a chromosome.
What does trisomic?
Having an additional chromosome.
Describe Down Syndrome.
An extra full or partial copy of chromosome 21.
(47, XX, +21) or (47, XY, +21)
Describe Klinefelter Syndrome.
- An extra X chromosome in males
(47, XXY) - Contain male sex organs
- Under-developed testes
- May have breast development
- Man is sterile
Describe Turner Syndrome.
- Missing an X chromosome in females
(45, XO) - Have female characteristics
-Under-developed ovaries
- Female is sterile
Describe Triple X.
- An extra X chromosome in females
(47, XXX) - Healthy and fertile
- Usually cannot be distinguished from XX females except by karyotype
Describe Jacob Syndrome.
- Apparently normal male
- Tall
- Aggressive
- (47, XYY)
Describe Edward Syndrome.
- Trisomy 18
- (47, XX, +18) or (47, XY, +18)
- Intellectual and physical disabilities
- Facial abnormalities
- Extreme muscle tone
- Early death
Describe Patau Syndrome.
- Trisomy 13
- (47, XX, +13) or (47, XY, +13)
- Intellectual and physical disabilities
- Wide variety of defects in organs
- Large triangular nose
- Early death
What is deletion?
Removal of a chromosomal segmant.
What is duplication?
Repeats a segment.
What is inversion?
Reverses a segment within a chromosome.
What is translocation?
Moves a segment from one chromosome to another non-homologous one.
Describe Cri du Chat Disorder.
- Partial deletion of chromosome 5
- Characteristic cat-like cry of affected children due to problems with the larynx and nervous system.
- Low birth weight and poor growth.
- Severe cognitive, speech and motor disabilites.
-unusual facial features wiith small head and jaw.
Describe Charcot-Marie-Tooth Disease.
- Duplication of a large region on the short arm of chromosome 17
- Inherited neurological disorder.
- Progressive loss of muscle tissue and touch sensation across various parts of the body.
