Exam 1 Flashcards
What is a gene?
The basic structural and functional unit of genetics
What is eugenics?
Idea that genetic selection should be used to improve the human race
What was wrong with the science behind eugenics?
There was no valid scientific evidence, it was anecdotal evidence (telling stories, testimonials)
How does hereditarianism compare to what we now know about the determination of human phenotype?
It is wrong
What social problems resulted from the eugenics movement?
Sterilized people, making decisions that affected other people profoundly, basically telling people they are worthless
Did Michigan sterilize individuals who clearly had genetic defects?
No they did it to “feeble minded” and “stupid” people as well
Does modern science give absolute answers to all questions involving human genetics?
No
What is hereditarianism and what is the invalid assumption it makes?
The idea that all human traits are determined only by genes.
What is a homolog?
pairs of chromosomes
What is a zygote?
a fertilized egg
What is a centromere?
a region of a chromosome to which spindle fibers attach, its how the chromosome moves around in a cell when it needs to
What is interphase?
The time between divisions in the cell cycle
What are somatic cells?
Any cell that isn’t reproductive
What are gametes?
a reproductive or sex cell that contains the haploid set of chromosomes
What is spermatocyte?
Diploid cells that undergo meiosis to form spermatids
What are spermatids?
The 4 haploid cells produced by meiotic division of a spermatocyte
What is spermatozoa?
The little swimmers
What is oocyte?
A cell from which the ovum develops from meiosis
What is a polar body?
Cells produced in female meiosis that will not function as gametes
What is an ovum?
The haploid cell produced by meiosis that becomes the functional gamete
What are diploid cells?
Cells with two copies of each chromosome (46)
What is a haploid cell?
cells with one set of chromosomes (23)
What do haploid cells form?
Gametes (sperm and egg)
How does a haploid cell turn back into a diploid cell?
Fusion of haploids with fertilization returns the number back to diploid (46)
What is a sex chromosome?
X or Y
What is an autosome?
Any non sex chromosome
What is the purpose of mitosis?
To make body cells. They duplicate an exact copy of 1 cell to 2 cells
What is the purpose of meiosis?
To produce the gametes or sex cells in 2 divisions
What are the similarities between mitosis and meiosis?
They both have cytokinesis during telophases, they both use spindle fibers to separate chromatids
What are the differences between mitosis and meiosis?
Mitosis produces 2 identical cells. Meiosis produces haploid cells from diploid parent cells
What is crossing over and why is it important?
The exchange of genes between homologous chromosomes. It is important because it produces genetic variety, allowing a species to adapt more easily to their environment
How does spermatogenesis differ from oogenesis (including the timing)?
In spermatogenesis 4 small spermatids are formed. In Oogenesis 1 egg is formed. Spermatogenesis starts around puberty in the testes. Oogenesis starts 2-3 months after birth
What is the function of a mitochondria?
To complete the breakdown of glucose, producing energy
What is the function of a nucleus?
To produce ribosomes
What is the function of a ribosome?
To aid in the production of proteins
How many autosomes are present in the body cell of a human being? In a gamete?
44 in a body (somatic) cell and 22 in a gamete
What is a chromosome?
Threadlike structures in the nucleus that carry genetic information
What is chromatin?
The DNA or protein components of a chromosome
How many chromosomes and chromatids do human haploid gametes contain?
23 of each
What are sister chromatids?
When two chromosomes share a pair (92)
In the cell cycle, at which stages do two chromatids make up one chromosome?
At the beginning of mitosis (G2)
Does the cell cycle refer mitosis as well as meiosis?
No meiosis is part of the life cycle
Why is cell furrowing important in cell division? If cytokinesis did not occur what would be the result?
If cytokinesis did not occur the cell would not fully divide, resulting in one cell with two nuclei, 2 sets of DNA, etc
During which phases of the mitotic cycle would the terms chromosome and chromatid refer to identical structures?
anaphase
What type of cels do humans need to produce in large quantities on a daily basis?
somatic cells
How can errors in the cell cycle lead to cancer in humans?
If a cell does not divide properly it can lead to cancerous cells
How many daughter cells are produced in mitosis and meiosis?
2 in mitosis, 4 in meiosis
How many chromosomes are there per daughter cell in mitosis and meiosis?
2n in mitosis, n in meiosis
Do chromosomes pair in mitosis and meiosis?
No in mitosis, yes in meiosis
Do the chromosomes replicate before division in mitosis and meiosis?
Yes in mitosis, no in meiosis
What is a summary of meiosis?
2 chromosomes pairs, chromosomes pair up (M1), separate, then sister chromatids separate to become individual chromosomes (M2)
What does mitosis result in? (visually)
4 straight lines
What is a testcross?
Crossing an organism with a dominant genotype to a recessive homozygous for a specific phenotype in order to determine dominant/recessiveness of the unknown genotype
What is a backcross?
The cross of an individual (F1) with one of its parents (F2) or an organism with the same genotype as a parent
What is epistasis?
the interaction of two or more non allele genes to control a single phenotype
What are the advantages and disadvantages of requiring more genetic testing of newborns?
Advantages include detecting a disorder early. Disadvantages include being invasive and potential injury`
Why were peas a better choice to experiment on than most animals or other plants?
- the presence of easily observable traits with contrasting forms
- produces many offspring in one cross
- short life cycle and ease in cross pollination
What is segregating during meiosis?
Gene pairs separate from each other during meiosis
What is the principle of independent assortment?
After segregation alleles are randomly reunited at fertilization
Which meiotic processes cause independent assortment?
During meiosis 1 the alleles split and then can recombine with genes from the other parent
How many alleles can occur on a single individual?
2
How many alleles can be passes on to a single offspring?
1
What is the difference between incomplete dominance and co-dominance?
incomplete: both alleles are blended (red + white = pink)
co-dominance: both alleles are shown (red + white = red and white splotches)
What is a male on a pedigree?
a square
How do Rh+ and Rh- relate to hemolytic disease of the newborn?
Rh+ mothers have no issues. Rh- mothers with Rh+ fetus have issues
What is hemizygous?
A gene present on the X chromosome that is expressed in males in both the recessive and dominant conditions
What is penetrance?
The probability that a disease phenotype will appear when a disease related genotype is present
What is expressivity?
The range of phenotypes resulting from a given genotype
What is assortative mating?
Nonrandom mating pattern where individuals with similar phenotypes and genotypes mate (similar body types mating)
What is consanguineous?
Marriage or mating among related individuals
What is pleiotropy?
the single gene controlling or influencing multiple phenotypes
What is a phenocopy?
an environmentally induced phenotype mimicking one usually produced by a single genotype
