Quiz 1 Flashcards
Heredity
The passing of traits from parents to offspring
Genetics
The scientific study of heredity and variation
Gene
A segment of DNA which codes for a particular trait
Locus
The location of a gene on a chromosome
What does the structure of a chromosome look like?
[refer to diagram in notes]
Sister chromatids
The double sets of chromosomes attached at the centromere
Centrioles
An organelle that produces spinal fibres. Also called centrosomes
Diploid
Cells have 2 sets of chromosomes (2n)
Haploid
Cells have 1/2 the normal sets of chromosomes
Polypoid
Cells have 3 or more sets of chromosomes
Chromosome
Found in the nucleus of eukaryotic cells. Made up of DNA. They occur in sets
How many chromosomes do humans have?
46
Interphase
The longest phase of the cell in which the cells perform all normal life functions, the cell grows in size, and the organelles and DNA are duplicated
Mitosis. What does it ensure?
The middle section of the cell cycle in which 2 identical diploid daughter cells are produced. It ensures each new cell has a nucleus with chromatin
Prophase
The DNA condenses and thickens to form chromosomes (coiled DNA) and the nuclear membrane starts to dissolve. Centrioles migrate to poles of cell and spindle fibres attach to centromere
Metaphase
Nuclear membrane completely dissolves and chromosomes line up along the middle of the cell
Anaphase
Each chromosome separates into two identical single-stranded parts (formally the chromosomes now sister chromatids). Sister chromatids are pulled toward end of each cell, because spindle fibers contract
Telophase
Single stranded chromosomes coil into thin strands of chromatin. Spindle fibers dissolve, and the nuclear membrane reforms
Cytokinesis
Cytoplasm and organelles separate. Two daughter cells form. In animal cells, cell pinches into two. In plant cells, a cell wall forms, dividing it into two parts
DNA
Deoxyribonucleic acid: a molecule that carries genetic information for cells, it makes up a chromosome
Chromatin
The genetic material which is made up of DNA strands
What is a gamete? What do they include? How are they produced?
They are haploid sex cells. They include egg and sperm cells. Produced by meiosis
What is fertilization? What is the product?
The joining/fusion of two gametes. The new cell produced is diploid, called a zygote.
Homologous chromosomes
Matching pairs of chromosomes. Each chromosome of the pair is composed of a pair of sister chromatids (the structure is a tetrad)
Meiosis? What are the 2 stages?
A two-stage cell division in which the resulting daughter cells have half the number of chromosomes as the parent cell. It produces four haploid gametes cells
Prophase 1
Chromosomes shorten and thicken. Nuclear membrane starts to dissolve. Sister chromatids come together as homologous pairs (this structures called a tetrad). Synapsis then occurs, causing crossing over
Metaphase 1
The tetrads migrate towards the center of the cell
Anaphase 1
Homologous chromosomes are pulled by spindle fibres and move to opposite poles. Reduction division occurs cutting number of chromosomes in half
Telophase 1
Nuclear membrane starts to reform and cell begins to divide. The new cells are haploid
Prophase 2
Nuclear membrane reforms and spindle fibres begin to reform
Metaphase 2
Sister chromatids line up NEXT to each other across the equator of cell
Anaphase 2
Sister chromatids software and move to opposite poles. Nuclear membrane starts to form around chromatids, now called chromosomes
Telophase 2 and cytokinesis
Cytoplasm and organelles divide. 4 haploid non-identical daughter cells (gametes) are produced.
Tetrad
The structure of homologous pairs
Synapsis and crossing over
Each sister chromatid intertwines with a sister chromatids from its matching homologous chromosome. The intertwined chromatids from different chromosomes break and reattach to each other, exchanging DNA
Reduction division
When only 1 of the sister chromatids from each homologous pair are found in each new daughter cell. (Cutting number of chromosomes in half)
Gametogenesis
The process where gametes are produced. Occurs in reproductive organs (plants: flowers, humans: gonads). Cells produced are haploid
Oogenesis
The process where mature eggs are produced in the ovaries. [refer to notes for diagram]
Spermatogenesis
The production of sperm cells in the testes. [refer to notes for diagram]
Random assortment
In metaphase 1 the chromosomes arrange into homologous pairs (across the cell’s equator) and depending on how they line up, a number of different combinations may be found in the gametes
How can we calculate the need of chromosome combinations for any diploid (2n) organism?
We can’t use 2^n, where n is the number of pairs
Largo types
A photograph of all the chromosomes of an individual. Useful for determine gender, diagnosing chromosome abnormalities which lead to health issues
What are chromosome abnormalities? What are the 2 kinds of errors?
Abnormalities that occur with chromosomes during meiosis. Type 1) changes in chromosomal structure. Type 2) changes in chromosomal number
Chromosomal structure changes
During crossing over, the chemical bonds that hold DNA together in the chromosome are broken, then reformed. Sometimes they don’t reform correctly! Also, sometimes non-homologous pairs cross over, producing chromosomes with genes not normally found in that chromosome.
What are the 4 types of errors in chromosomal structure changes?
A) deletion - a chromosome is missing a piece of DNA
B) duplication - a chromosome has an extra piece of DNA
C) inversion - the piece of DNA gets flipped upside down
D) translocation - a chromosome shares a piece of DNA with a non-homologous pair
Changes in chromosomal number. What is non-disjunction?
Sometimes homologous pairs of sister chromatids don’t separate properly. This is called non-disjunction and can occur in anaphase 1 or 2
What are the 2 kinds of errors of changes in chromosomal number?
A) monosomy: missing 1 chromosome. Kurds when a single chromosome is in place of a homologous pair. Ex) in turned syndrome there is 1 X chromosome missing
B) trisomy: 1 extra chromosome. Occurs when there are 3 chromosomes in place of 1 homologous pair. Ex) in Down syndrome there is an extra chromosome #21
What are the 4 non-disjunction disorders?
Patau syndrome Turner syndrome Klinefelter syndrome Down syndrome Edwards syndrome
Patau syndrome
Chromosome #13 has 3 copies of genetic material. Causes cleft lip, extra fingers and toes
Klinefelter syndrome
Results in an extra copy of the X chromosome in each cell. Interferes with male sexual development and age delay for learning to walk
Turner syndrome
The deletion of the second X chromosome. Causes short stature, puffy hands and feet, curvature of spine, overweight, lazy eye, etc.
Down syndrome
When you have an extra chromosome #21. Causes extra space between big toe and 2nd toe, and hyper-flexibility
Edwards syndrome
Extra copy of chromosome #18. Causes mental delay and smaller head
Recombinant DNA
Taking one chromosome and putting it into a completely different cell. (From one species to another). Ex) GMO: genetically modified organism. Like strawberries
Artificial insemination
Inserting sperm cells into the uterus of am the female organism to fertilize an egg. Used commonly in animal breeding and livestock
In vitro fertilization
“Test-tube baby”. Manually combing sperm and egg in a lab dish and transferring the embryo to the uterus. Ex) dairy cows
Cloning
Removing a mature somatic cell (such as a skin cell) from an animal they want to copy. Then they transfer the DNA of the donor into the egg cell (which has had its own nucleus containing DNA removed). Ex) people clone animals so farmers can raise them for human organ transplants
