Unit A Section 3.1 Flashcards
How many genes can a human have?
They estimated that humans have about 30 000 genes.
What are blueprints?
Every multicellular organism on Earth contains a blueprint for making a copy of itself in each of its body cells.
What could store so much information, and pass it on from generation to generation?
deoxyribonucleic acid,
What is deoxyribonucleic acid?
- a large molecule first found in cells’ nuclei is responsible for storing such information and passing it on.
- DNA for short is the inherited material responsible for the variation.
- DNA was first identified in 1869
- Because every organism has so many physical and chemical characteristics, there is a lot of DNA in a cell.
Who can have deoxyribonucleic acid?
-All living organisms contain DNA in their cells.
the cells of mammals and plants contain a nucleus,
- DNA is found in the nucleus.
- bacteria to plants and animals—scientists found DNA in all of them
How could the blueprints for so many different organisms be passed on by what seemed to be exactly the same molecule?
the same chemical building blocks could carry such a wide range of instructions needed for the diversity we observe in the living world.
What is the structure of a DNA molecule?
- The DNA molecule can be compared to a ladder that has been twisted into a continuous spiral.
- Each individual rung pairs up just two of the following four chemicals: guanine (orange), cytosine (blue), adenine (green), and thiamine (violet), or G, C, A, and T, for short
What are the four DNA chemicals?
- guanine (orange),
- cytosine (blue),
- adenine (green),
- and thiamine (violet),
- or G, C, A, and T, for short
What is a genetic code:
- is based on arranging the four chemical “letters” into “words,” or instructions, that describe how to make any particular organism.
- Paired chemicals make up the “rungs” of the DNA “ladder” and form the genetic code
How can such a large amount of DNA into their cells?
- organisms arrange their DNA into packages.
- These packages are called chromosomes.
Where are the chromosome located?
- the chromosomes are located inside the cell nucleus
- All of our nuclei, except for those in the gametes, must have a complete set of chromosomes.
- One chromosome contains only part of the instructions for making a human.
How many chromosomes does each human nucleus cell contain?
- Each human cell nucleus, for example, contains 46 chromosomes.
- For dogs, a complete set has 78 chromosomes
- for cats, the number is 38.
How are the chromosomes organized?
- In most familiar organisms, the chromosomes are organized into pairs.
- body cells of a human contain 23 pairs of chromosomes
- a dog’s body cells contain 39 pairs
- a cat’s body cells contain 19 pairs
- chromosome number varies from one species to another
- the composition of the chromosomes varies as well
What are genes?
- genes are responsible for the inheritance of an organism’s characteristic features.
- A single gene is an uninterrupted segment of DNA, which contains coded instructions.
Where are genes located?
- Genes are located on the chromosomes.
- Each chromosome contains numerous gene locations
