Lecture 2B (more information about what’s going on inside the cell)
Structure of DNA
What’s a protein?
- It’s a ______made of large molecules
- It’s an essential part of all living organisms, especially as ______components of body tissues, such as hair, muscle, collagen, etc.
- Proteins may act as enzymes and antibodies
______do most of the work in cells, and they are required for the structure, function, and regulation of the body’s tissues and organs
The instructions for making a protein are found within ______
DNA is the genetic material that stores information regarding its own replication
DNA also stores information regarding the order in which amino acids are to be joined together to make a ______
DNA is made of ______
Every nucleotide is a molecular complex of three types of unit molecules:
- Pentose sugar
- Nitrogen-containing ______
There are four different types of nucleotides in DNA
- The base can be one of the ______, adenine or guanine
- Each of these has a double ring
- The base can be one of the pyrimidines, thymine or cytosine
- Each of these have a ______ring
- The structures are called bases because their presence raises the _____ of a solution
Nucleotides join in a definite sequence
- The nucleotides form a linear molecule called a ______, in which the backbone is made up of phosphate-sugar-phosphate-sugar, with the bases projecting to one side of the backbone
- Since the nucleotides occur in a definite order, so do the ______
DNA is double stranded, with the two strands twisted around each other in the form of a double ______
The two strands are held together by hydrogen bonds between purine and pyrimidine bases
When unwound, DNA resembles a ______
- The sides of the ladder are made entirely of phosphate and sugar molecules and the rungs are made only of complementary paired bases
Complementary based pairs?
- thymine is always paired with ______
- guanine is always paired with ______
The sequence of nucleotides in DNA directs the order of ______acids to be joined to make a protein.
There are only four nucleotides, but there are 20 amino acids found in proteins.
So, one nucleotide ______code for one amino acid
So, it takes a ______of nucleotides to code for an amino acid.
If we think of a nucleotide, or the base of the nucleotide, as the letter in a code word, we could have combinations of two letters in each code word for more than 4 amino acids
To code for more than 16 amino acids, it takes a group of three nucleotides in a “code word”
The “code words,” here, are called ______
A few interesting things about codons:
- Most amino acids have more than one ______
- Each triplet codon has only one meaning
- The code has start and ______signals
- There’s only one start signal, but there are three stop signals.