3 Flashcards
What are the 3 functions of cell division?
- Reproduction: usually refers to single-celled organisms that reproduce asexually)
- Growth, renewal, repair- ( usually refers to multicellular organisms)
- Maintenance of an adequate surface area-to-volume ratio
asexual reproduction
Asexual: reproduction by binary fission or mitosis. Only on organism/cell involved that divides into two .daughter cells are identical.
Sexual reproduction
Sexual: reproduction throught the fusion of male and female gametes/sex cells. Gametes are produced furing meiosis. Two organisms are involved. The offspring produced via sexual reproduction are genetically different than either of the parents. This allows genetic diversity among the offspring.
DNA
the genetic material ( deoxyribonucleic acid)
Chromatin
A loosely arranged form of DNA seen when a cell is not actively dividing
Chromosome
A tightly condensed form of DNA seen when a cell is actively dividing. ( 1 chromosome= one molecule of DNA)
Chromatid
One half of a duplicated chromosome
Centromere
Constricted region made of DNA that holds two sister chromatids together before they separate;also, the intended or constricted region on a chromsome; sometimes the centromere is located toward the middle of the chromosome, sometimes it is off center, and sometimes it is more toward the end. The location of the centromere is one way that chromosomes can be identified.
Histones
little protein spools that help organize DNA
Nucleosomes
histone proteins with two wraps of DNA on them. These are important in organizing DNA because this is how the DNA strand is condensed. ( This is how approx. six-feet of DNA can be compacted into the nucleus of a single cell.
how many chromosomes do humans have?
46
Does the amount of chromosomes relate to the size or complexity of an organism?
no.
define mitosis. Where does it occur in the body?
ordinary nuclear division for growth and repair; the chromosome number remains constant; occurs in body (somatic) cells
Define cytokinesis
division of the cytoplasm and its contents
What is a cleavage furrow?
in animal cells, forms when the cell invaginates all the way around and pinches itself into two daughter cells.
What is a cell plate?
In plant cells, it forms to divide the parent cell intwo two daughter cells.
mitosis
the ordinary nuclear/cell division for growth, repair and replacement of old worn out cells.
Describe the process of mitosis?
see drawing on back of review paper.
How many daughter cells are produces, and are they identical?
produces 2 daughter cells, they are identical to their parents and eachother.
What causes a cell to continue to divide or prevent it from doing so?
1) Outside influences, such as hormone’s or growth factors
2) Adhesion to a solid Surface- The cytoskeleton of cells has to have a solid surface to push against in order to divide
3) Contract inhibition- Normally, when neighboring cells touch each other, they stop dividing.
how is cancer related to mitosis?
Cancer is uncontrolled cell division ( mitosis). Cancer cells do not grow and divide faster than normal cells. The problem is that they do not stop growing, dividing or moving on contact. Cancer cells crawl over other cells, invade healthy tissues, and multiply into masses called tumors.
Metastasis
The spread of cancer cells from their site of origin to other parts of the body.
Benign tumor
-noncancerous
- cells remain differentiated
-encapsulated
-uniform shape
malignant tumor
-cancerous
-cells are undifferentiated
-not encapsulated
- not uniform in shape, can have “feelers”
- cna, and often do, spread/ metastasize
-life threatening
Define the 3 main types of cancer treatments:
Slash, Burn and poison
Slash: surgery to remove tumor. for many benign tumors, surgery alone may be sufficient.
Burn: radiation therapy; often effective against malignant tumors that have not yet spread/metastasized.
Poison: chemotherapy; use of systemic drugs to disrupt cell division; used to treat tumors that have spread/ metastasized throughout the body.
Define Meiosis. Where does it occur in the body? What is its function?
nuclear division for the production of eggs and sperm; the chromosome number is reduced by half; process inly occurs in the ovaries of females and the testes of males.
Diploid
2N where N represents one complete set of chromosomes; “ Chromosomes, and the genes they carry, come in pairs.” All body ( somatic) cells are diploid with the exception of sex cells ( egg and sperm).
Two complete chromosomes one from each parent.
Haploid
N there is only one complete set of chromosomes in a haploid cell. The only haploid cell in animals are the sex cells ( eggs and sperm).
Gametes
sex cells/eggs and sperm
Homologous chromosomes
pairs of chromosomes that carry genes for the same traits although the expression of the traits may be different for each. One homolog comes from the mother and the other homolog comes from the father.
Describe the process of meiosis I and Meiosis II
meiosis I involves the reduction divsion where the number of chromosomes is reduced by half. Meiosis II involves the seperation of sister chromatids.
Features of meiosis:
a) two nuclear divisions to complete the process
b) homologous chromosomes separate first, then the sister chromatids separate
c) diploid (2N)–haploid ( N)
d) produces four daughter cells that are different from the parent cell and different from each other.
Describe the process of meiosis
( refer to drawing in notebook)
Compare meiosis and mitosis. What are the difference and similarities between these processes?
( See “ Features of mitosis” and “ Features of meiosis”)
What are spermatogenesis and oogenesis? How many functional end products are produced by each od these meiotic processes
spermatogenesis: formation of sperm cells through the process of meiosis. Each round of spermatogenesis produces 4 viable/functional sperm cells.
oogenesis: formation of egg cells through the process of meiosis. Each round of meiosis produces on viable/functional egg and two or three polar bodies. Polar bodies will never develop into an egg. They disinegrate.
Independent assortment of chromosomes:
For each pair of homologous chromosomes ( one from mom and the other from dad) situated side-by-side during meiosis, the maternal chromosome and the paternal chromosome separates independently of other homogenous pairs. The resulting eggs or sperm will have a combination of maternal and paternal chromosomes.
Random fertilization:
Has to do with the odds that any particular sperm cell of millions that are released will be “the one” to fertilize the egg cell.
Crossing over:
occurs during meiosis I when the homologous pairs are side-by-side. The maternal and paternal homologs exchange material ( genes) with each other. Usually, it is an equal exchange ( but not always). The significance of crossing over is that it enhances genetic diversity. This is how genes get “ shuffles” between homologs so that the gametes produced contain chromosomes with a combination of genes from the maternal and paternal parents.
What is Karyotype?
An arrangement of the chromosomes of an individual. The chromosomes are arranges from the largest homologous pair to the smallest homologous pair. The sex chromosomes are the 23rd pair.
What kinds of information can one learn by examinig a karyotype?
a) sex (gender)
b) if there are extra or missing chromosomes ( such as Trisomy 21 or Turner syndrome females that have only one X chromosome)
c) broken chromosomes ( There are some genetic disorders caused by chromosomes that are missing a piece )
d) translocations ( where a piece of one chromosome breaks off and goes and sticks on a different chromosome)
What can’t you see on a karyotype?
Small things at the gene level. ( i.e. eye color, hair color, etc.)
What are autosomes? How many pairs do humans have?
any chromosomes that are NOT sex chromosomes. Humans have 22 pairs of autosomes.
What are sex chromosomes? What sex chromosomes in humans determine femaleness? What sex chromosomes
in humans determine maleness?
Sex chromosomes determine the sex (gender) of the organism. Humans have one pair of sex chromosomes. Females have a pair of X chromosomes (XX) usually. Males have one X chromosome and one Y chromosome (XY) usually.
What is nondisjunction?
Is the failure of chromosomes to separate
properly during meiosis. The cause of monosomy and trisomy
is nondisjunction.
What causes Trisomy 21 (Down syndrome)? What is the correlation with the mother’s age?
Down syndrome is usually (96% of the time) caused by having three copies of chromosome 21.
What are the genotypes and symptoms of the following
disorders? (Turner syndrome, metafemale, Klinefelter
syndrome, XYY male
Turer Syndrome- XO
Metafemale- XXX
Klinefelter syndrome- XXY
XYY male-XXY
Who was Gregor Mendel?
Gregor Mendel (1822-1884) is considered to be the “father
of genetics.” He was an Austrian monk who taught science and was also trained in math.
Genotype
the set of genes or alleles possessed by an organism. The genotype remains constant throughout the life of the organism. (TT, Tt, and tt
are genotypes.)
Explain the significance of Mendel’s experiments compared to the experiments of others before him.
(What things did Mendel do that allowed him to come to the conclusions that he did?)
Mendel did most of his work on garden peas around
1860.
* Peas are easy to grow and have a short generation time.
* Mendel gathered data and analyzed it statistically.
* Mendel spent about two years making sure he had true-
breeding peas. (This means the offspring would show
the same traits as the parents.)
* Mendel kept accurate and detailed records of the inheritance of seven traits in peas.
Allele
an alternative form of a gene. (You have two alleles (genes) for every trait.)
P generation
The parental generation
dominant allele
allele that masks the expression of
another allele.
heterozygous
having two different alleles (Tt) for a given trait. Heterozygotes are known as hybrids.
Recessive allele
allele that has its expression masked in
the presence of a dominant allele
Phenotype
Characteristics that are expressed, but not necessarily seen. Phenotypes may be morphological (physical), physiological (chemical), and/or
behavioral. The phenotype may change continually throughout the life of the organism. (We use word descriptions for phenotypes. Examples would be: tall, short, freckled, Widow’s peak, blue-eyed, brown-haired, etc
Homozygous
having two identical alleles for a given trait. The pairs of alleles will be both dominant (TT) or both recessive (tt)
F1 generation
the first filial generation, first generation of offspring
F2 generation
The second filial generation= offspring obtained from crosses of F1 individuals
What is Mendels rule/law of segregation
1) Each organism contains two factors ( genes) for each trait. These two factors separate during the formation of gametes so that each gamete contains only on factor ( gene) for each trait.
2) Upon fertilization, the new organisms will have two factors (genes) for each trait, one from each parent.
Monohybrid cross
A cross involving only one trait.
Be able to do some mono hybrid cross genetics problems
First know what trait is dominant.
E= unattached earlobes ( dominant)
e= attached earlobes ( recessive)
Problem A: Suppose a man homozygous for unattached earlobes reproduces with a woman who has attached earlobes. What types of earlobes, and in what proportion, will their children have?
answer: See back of study guide
What is the difference between a genotypic ratio and a phenotypic ratio?
Genotypic= the proportions of different genotypes obtained among the offspring in a cross.
Phenotypic ratio= the proportions of different phenotypes obtained among the offspring in a cross
What is a testcross? For what purpose is it used?
A testcross is a cross in which one individual with a dominant phenotype is crossed to an individual with a
recessive phenotype.If any offspring from a testcross show the recessive trait,then the dominant phenotype individual must be heterozygous.
Define dihybrid cross
A genetic cross that involves two different traits/characteristics
What is Mendels rule/law of independent assortment?
States that members of one pair of genes separate independently of members of a second pair of genes. All possible combinations of alleles can show up in the gametes.
How do you tell a genotype from a gamete when they are written in symbolic ( letter) terms?
Genotypes are diploid. ( genes come in pairs) ex. Aa, AA, AaBb,ccDdEe,XxYyZz
Gametes are haploid. (There is only a single copy of an allele or gene in the gametes.) ex. A,a,aB,Ab,cDe,xYz
Given a particular genotype, be able to figure out the different kinds of gametes
worksheet number 9 part b
use the FOIL method
What is codominace?
a type of inheritance in which two versions (alleles) of the same gene are expressed separately to yield different traits in an individual. Ex: AB blood type
Multiple alleles
There are more than one allele.
What is the RH factor? What must the phenotypes of the parents be for the complications to arise?
The Rh factor is a separate protein that may be on the surface of red blood cells.
What is pleiotropy?
the production by a single gene of two or more apparently unrelated effects.
ow do Marfan Syndrome and sickle-cell anemia relate to pleiotropy?
some of the multiple effects of inheriting two copies of the recessive sickle-
cell anemia alleles are: lack of oxygen to tissues, muscle
cramping, anemia (because our bodies send weird-shaped red blood cells to the spleen to be destroyed), kidney damage, problems with lungs, and other vital organs, et
What is polygenic inheritance? Give examples of traits that exhibit polygenic inheritance.
olygenic inheritance is a pattern of inheritance where
the genetic traits are controlled or determined by several pairs of genes/alleles rather than just one pair of gene/alleles.Polygenic inheritance is also called additive or quantitative inheritance because each contributing allele adds a bit more to the expression of the trait.Examples of polygenic traits include: height, skin color,eye color, weight, and any others where we see a continuous range in the phenotype.
How do genes and the environment affect phenotype?
Most of our genetic traits are not 100% genetic. Both
genes and the environment work together to determine the phenotype. Even traits like height can be affected by the environment. You could inherit genes for the potential to be really tall, but if you don’t get enough good nutrition to feed your body during critical growing years, you may not realize your full potential as far as height is concerned and be somewhat stunted in your growth. We know that skin color can be affected (temporarily) by how much time you spend out
in the sun.
Define sex-linked genes
genes that are located on the sex chromosomes
x-linked/sex-linked genes+ examples
genes located on the x chromosomes Ex: red-green colorblindness, hemophilia, fragile-X syndrome
Y-linked
genes located on the Y chromosomes
