Biology 2nd Semester 2013 Study Guide – More Terms to Know
Genetics (Chapters 10 and 11)
Crossing Over
 Exchange of segments of DNA between a pair of homologous chromosomes during prophase I of
meiosis.
Gamete
 Another name for sperm and egg cells.
 A gamete has ½ the genetic material as the parent cell.
 Sperm and egg cells combine to form a fertilized egg during meiosis.
Fertilization
 The process by which egg and sperm combine to produce a new cell.
Gregor Mendel
 A scientist who lived in the 1800’s and studied how traits are inherited using pea plants.
Mitosis

.
The cell division process that produces 2 cells
genetically identical to the parent cell.



2 IDENTICAL ↗
Meiosis
The cell division process that occurs only in
sexually reproducing organisms.
Produces 4 gametes, each one is genetically
unique.
Assures genetic variation in organisms
↖ 4 DIFFERENT
Genetics (Chapters 12 & 13)
DNA

DNA stands for deoxyribonucleic acid
o Made of nucleotides
 A nucleotide has three parts:
 A phosphate group
 A five-carbon (pentose) sugar called deoxyribose
 A nitrogen base
o Adenine (A)
Nucleotide
o Guanine (G)
o Cytosine (C)
o Thymine (T)
DNA Replication
 the DNA process of making an exact copy of itself.
 nitrogen bases are complementary
o A bonds with T
o G bonds with C
Original strand → CTGGAC
New strand → GACCTG
DNA Mutations
 A permanent change in a cell’s DNA.
 Produces a protein different from the original.
How proteins are made
DNA
Takes place
Transcription
in the nucleus
RNA
Translation
Protein
in the ribosome
Transcription is the process that makes messenger RNA (mRNA).
Translation is the process that translates the nucleotides to amino acids (proteins).
DNA vs RNA
•
•
•
•
•
•
Deoxyribonucleic acid
Contains genetic information
Has 2 STRANDS
Contains the sugar DEOXYRIBOSE
Nitrogen bases = guanine, cytosine,
adenine and THYMINE
G matches with C and
A matches with T
How are DNA and RNA the same?
 Both have nucleic acids
 Both have guanine, cytosine, and adenine
 Both made of nucleotides
 Both have phosphate groups
•
•
•
•
•
•
Ribonucleic acid
Contains information to make proteins
Has only a SINGLE STRAND
Contains the sugar RIBOSE
Nitrogen bases = guanine, cytosine,
adenine and URACIL
G matches with C and
A matches with U
How are DNA and RNA DIFFERENT?
Codons
• A nucleotide sequence (triplet) in DNA and RNA.
 When the original DNA strand makes a strand of mRNA----o A bonds with U
o C bonds with G
o AND…… T bonds with A
Original DNA strand→ A C G T T A C T T A T T
mRNA strand→
UGCAAUGAAUAA
↓
is made of
↓
Amino Acid Sequence
 Shown by first 3 letters, for example
o Cysteine=Cys
o Leucine=Leu
o Lysine= Lys
What is the Amino Acid Sequence for
U G C A A U G A A U A A?

Look at the Genetic Code→→→
o UGC=Cysteine
o AAU=Asparagine
o GAA= Glutamate
o UAA= stop
The Amino Acid Sequence → Cys-Asp-Glu-stop
Genetic Code
AND FINALLY ………….
Humans share over 90% of their DNA with primates.
Scientists believe humans and primates are similar because
millions of years ago we had the same ancestor.
GOOD LUCK ON YOUR FINALS!
DK
5/2013