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Inheritance occurs because of what?
What are genes made of?
What does a gene do?
provides the information needed to put amino acids in the right order to make one protein
What is DNA made of?
What are the three parts of a nucleotide?
- Sugar (deoxyribose)
- A phosphate
- A base
What are the four possible bases of a nucleotide?
What is the structure of DNA?
double helix (2 strands) connected by the bases in the middle
Who found the DNA structure?
James Watson, Francis Crick, Rosalind Franklin
Which of the three parts of a nucleotide make the backbone of DNA?
sugar and the phosphate (sides of the ladder)
What holds the two strands of DNA together?
hydrogen bonding between bases
What are the two strands of DNA in the helix?
anti-parallel (the same distance apart, but each strand starts at opposite ends of the DNA)
Why do bases always pair?
so that a base with one ring is paired with a base with two rings
What does DNA use as its alphabet?
What happens by putting bases in a different order?
you can make different proteins
What is making two identical double helixes?
What are the parts for DNA replication?
- Parent DNA strands
- More nucleotides to make the new strand
What means each new DNA helix has one new and one old DNA strand?
What are the steps to replication?
- An enzyme called helicase unwinds the helix to make a replication bubble.
- A second enzyme (DNA polymerase) pairs up the strands with new nucleotides, then connects the backbone of the new nucleotides.
- A third enzyme (DNA ligase) attaches the completed pieces together until it is one long strand of DNA.
How rare is it to have a mistake in DNA strands?
around 1 mistake for every billion base pairs
What is a change in the sequence of bases in DNA?
How can mutations happen?
due to exposure to things that damage DNA, such as chemicals, sunlight, and cosmic rays
What are the types of mutations?
Which type of mutation is a small error and does not affect the gene?
Which type of mutation is a large error and makes the whole gene wrong and is less likely to survive?
Which type of mutation is a small error and makes the gene better and may protect against AIDS?