Heredity and Genetics Quiz 2 Study Guide
ANSWER KEY (Part 2)
17. What are proteins and what are they made of?
Proteins are large biological molecules made up of long chains of amino acids. Proteins are
part of every cell and are involved in many cell functions. Each protein has its own sequence
of amino acids. Each kind of protein has its own special shape. Because proteins they come
in many shapes and sizes, they have diverse roles in the body. The specific shape of a
protein causes it to have only one function. The shape (or structure) of a protein determines
its function.
18. Why are proteins important?
Proteins have many functions in all living things and serve as building blocks for life. Their
many shapes allow them to have many functions. For example, proteins can be part of cell
structures such as muscle cells or ligaments. A protein called hemoglobin is in red blood
cells and helps the cells carry oxygen. Other proteins make up antibodies and are part of the
body's immune system. Special proteins called enzymes are important because they speed
up and slow down different chemical reactions. All together, these proteins are important
because they form the structure of animal bodies and allow them to function.
19. Where and how are proteins created?
Proteins are created by cell structures called ribosomes. Ribosomes are located within the
cytoplasm of the cell. To make a protein, a cell must put a chain of amino acids together in
the right order. First, it makes a copy of the DNA instruction in the cell nucleus, and takes it
into the cytoplasm in the form of mRNA. The mRNA attaches to the ribosome and the
ribosome reads the DNA code from the mRNA. The ribosome then connects the chains of
amino acids to form many copies of the protein, which fold into shape as they are produced.
20. What is meant by DNA → RNA → Protein?
DNA carries the genetic information of a cell and consists of thousands of genes. Each gene
along the DNA strand serves as a recipe on how to build a protein molecule. The sequence
(order) of genes in along the DNA will determine the type of protein that is made. The phrase
"DNA → RNA → Protein" means that the DNA is the set of instructions for the cell to build
proteins. The DNA is the set of instructions and is carried to the ribosome by the RNA. The
RNA leaves the nucleus and delivers the code to the ribosome, which then uses the code to
build proteins out of amino acids.
Diagrams
1. Label and describe diagrams of DNA (including all
of the base pairs)
DNA is a nucleic acid. DNA is shaped like a twisted
ladder, called a double helix. The DNA molecule sides are
made up of a sugar phosphate chain. The "rungs" of the
ladder are made up of the four building block nitrogen
bases. The four nitrogen bases in the DNA alphabet are
adenine (A), cytosine (C), guanine (G) and thymine (T).
The base pairs always match up in an A/T and C/G
pattern.
2. Label and describe diagrams of the scale and order of structures, from base pair to
gene to DNA to chromosome
Diagram A shows the order structures from base pair to gene to DNA to chromosome.
On the right side of the diagram is a drawing of base pairs. Base pairs match p in A-T
and C-G combinations. Base pairs make up the smallest unit in the DNA. A sequence
(group) of base pairs make up a gene- which is a section of DNA. There are many genes,
which are made of many base pairs, that make up DNA. DNA winds up into
chromosomes, which are located in the nucleus of each cell.
3. Label and describe diagrams of mitosis and meiosis
Mitosis and meiosis are both are types of cell division. Both result in the creation of daughter
cells. Mitosis results in two identical diploid daughter cells (with 100% of the chromosomes
as the parent cell), and meiosis results in four haploid daughter cells. The four daughter cells
have 50% of the chromosomes as the parent cell. The haploid cells are either egg or sperm.
Mitosis
Meiosis
4. Label and describe a diagram of protein synthesis
To create proteins in cells, the DNA code must be copied. The DNA splits apart and mRNA
forms. the mRNA is a copy of one-half of the DNA. The mRNA leaves the cell nucleus, and
travels into the cytoplasm. In the cytoplasm, the mRNA attaches to the ribosome. The
ribosome reads the DNA code from the mRNA. The ribosome then connects the chains of
amino acids to form many copies of the protein, which fold into shape as they are produced.