Answer:
Hershey and Chase experiment confirms that DNA is the genetic material of the living organism, not the RNA or protein. They also got a noble prize for this discovery.
Hershey and Chase use the radioactive sulfur to label the proteins and distinguish them from the DNA because DNA do not contain sulfur. The radioactive label phosphorus was used to label the DNA as phosphorus is specific to DNA as they wants to know exactly the genetic material. They do not use the radioactive carbon and nitrogen because both carbon and nitrogen are present in DNA and RNA. This labeling may produce confused result as it label both DNA as well as protein. The result o radioactive phosphorus and sulfur determines that DNA is the genetic material of the organism.
Answer:
archaeabacteria ( context clues can often give the answer :)
Growth and repair
creation of gametes (sex cells)
method of reproduction in unicellular organisms
Binary Fission - type of reproduction that occurs in bacterial cells, single celled organism splits and becomes two identical organisms
Chromosomes and DNA
Chromosomes are DNA wrapped around proteins to form an X-shaped structure.
The diagram will help you see the relationship.
1. Chromosomes are found in the nucleus
2. Chromosomes are made of DNA
3. Sections of chromosomes are called genes
DNA - deoxyribonucleic acid (it is the genetic code that contains all the information needed to build and maintain an organism)
Chromosome Structure
Chromosome Numbers
Each organism has a distinct number of chromosomes, in humans, every cell contains 46 chromosomes. Other organisms have different numbers, for instance, a dog has 78 chromosomes per cell.
Somatic Cells - body cells, such as muscle, skin, blood ...etc. These cells contain a complete set of chromosomes (46 in humans) and are called DIPLOID.
Sex Cells - also known as gametes. These cells contain half the number of chromosomes as body cells and are called HAPLOID
Chromosomes come in pairs, called Homologous Pairs (or homologs). Imagine homologs as a matching set, but they are not exacly alike, like a pair of shoes.
Diploid cells have 23 homologous pairs = total of 46
Haploid cells have 23 chromosomes (that are not paired) = total of 23
Homologous Chromosomes
Sex Determination
Chromosomes determine the sex of an offspring. In humans, a pair of chromosomes called SEX CHROMOSOMES determine the sex.
If you have XX sex chromosomes - you are female
If you have XY sex chromosomes - you are male
During fertilization, sperm cells will either contain an X or a Y chromosome (in addition to 22 other chromosomes - total of 23). If a sperm containing an X chromosome fertilizes an egg, the offspring will be female. If a sperm cell containing a Y chromosome fertilizes an egg, the offspring will be male.
Creation of a Zygote
When two sex cells, or gametes come together, the resulting fertilized egg is called a ZYGOTE
Zygotes are diploid and have the total 46 chromosomes (in humans)
Karyotype
A karyotype is a picture of a person's (or fetus) chromosomes. A karyotype is often done to determine if the offspring has the correct number of chromosomes. An incorrect number of chromosomes indicates that the child will have a condition, like Down Syndrome
Compare the Karyotypes below
Notice that a person with Down Syndrome has an extra chromosome #21. Instead of a pair, this person has 3 chromosomes - a condition called TRISOMY (tri = three)
Trisomy results when chromosomes fail to separate - NONDISJUNCTION - when sex cells are created. The resulting egg or sperm has 24 instead of the normal 23.
Other conditions result from having the wrong number of chromosomes:
Klinefelters Syndrome - XXY (sex chromosomes)
Edward Syndrome - Trisomy of chromosome #13
Answer:
This question lacks options, the options are:
A. All 270 tall plants were heterozygous
B. All 270 tall plants were homzygous.
C. Only 90 plants were homzygous.
D. All dwarf plants were homzygous.
The answer is D.
Explanation:
This question involves a single gene coding for height in pea plants. The allele for tallness (T) is dominant over that of dwarfness (t). This means that a dwarf plant can only be homzygous recessive (tt) while a tall plant can either be homzygous (TT) or heterozygous (Tt).
According to the question, two tall heterozygous pea plants were crossed i.e. Tt × Tt. Based on this cross, a phenotypic ratio of 3:1 is expected, which is in accordance with the 270 tall plants and 90 dwarf plants (360 total) that was obtained in the cross. Since dwarfism in pea plants is a recessive trait, this means that all the dwarf plants produced in this cross (90) were homzygous (tt).
Answer:
Option (d).
Explanation:
Telomere may be defined as the repetitive DNA sequence present at the ends of the chromosomes. Telomeres consists of the nucleotide sequence rich in G and consists of vertebrate sequence AGGGTT.
The mutation in telomerase enzyme can cause the excessive replication of the telomeres. These leads to the excessive cellular proliferation and makes the cell immortal. This extensive growth of telomere is one of the maine reason of the cancer development.
Thus, the correct answer is option (d).
