Unit 5 Review
Honors Biology
DNA structure & replication
OBJECTIVE 1
Covered by:

POGIL worksheet (okay to use in
portfolio since we did not do the lab)
Structure & Function
In nucleus (eukaryotes) –
never leaves
 Nucleotides

◦ Monomer of DNA
◦ Deoxyribose sugar,
phosphate, nitrogen base

Base pairs
◦ Adenine – Thymine
◦ Guanine – Cytosine


Double stranded helix
Codes for proteins –
very important molecule!
Replication
Copy DNA exactly
to pass to daughter
cells (for mitosis)
 Necessary for each
cell to have full set
of instructions to
make proteins

Gene expression
OBJECTIVE 2
DNA vs. RNA vs. Protein

DNA codes for
proteins
◦ Ex: “boss”

RNA helps make the
protein
◦ Ex: “workers”

Protein
◦ Monomer – amino acid
◦ Proteins have many
functions… think of
your projects!
◦ Ex: “product”
RNA Structure
In nucleus
(eukaryotes) and
cytoplasm/ribosomes
 Nucleotides

◦ Monomer of RNA
◦ Ribose sugar,
phosphate, nitrogen
base

Base pairs
◦ Adenine – Uracil (NO
THYMINE)
◦ Guanine – Cytosine

Single stranded helix
Types of RNA

mRNA – messenger
◦ Carries DNA message
to ribosome

tRNA – transfer
◦ Transfers amino acids
to ribosome

rRNA – ribosomal
◦ Where amino acids
are assembled to make
protein
Transcription
DNA is transcribed (copied) into a
mRNA sequence
 mRNA leaves nucleus to carry code to
ribosome
 Animation

Translation
mRNA goes to a ribosome, tRNAs bring
in amino acids to make a protein
 Animation

Gene Expression

Only genes for proteins a cell needs will
be expressed
Mitosis & Meiosis
OBJECTIVE 3
Haploid vs. Diploid
-ploid = sets of
chromosomes
 Diploid = 2 sets of
chromosomes (2n)

◦ Somatic (body) cells
◦ Made by mitosis
◦ Ex: human skin cell 2n=
46 (2 sets of 23)

Haploid = 1 set of
chromosomes (1n)
◦ Gametes (sperm and egg)
◦ Made by meiosis
◦ Ex: human sperm cell
1n=23 (1 set of 23)
Mitosis
Allows for growth of organisms (somatic
= body cells), asexual reproduction
 Produces 2 identical cells to parent

◦ Chromosome # in parent cell = chromosome
# in daughter cells

Diploid cells  diploid cells
Meiosis
Allows sexually reproducing organisms to make
gametes (sperm, egg)
 Produces 4 haploid, genetically different cells

◦ Crossing over = genetic variation
◦ Chromosome # in daughter cells is HALF the
chromosome # in parent cell

Diploid cells  haploid cells
Stem cells, differentiation, & specialization
OBJECTIVE 4

Specialization
◦ Cells take on specific
jobs
◦ Ex: neuron

Differentiation
◦ When a cell becomes
specialized, expresses
specific genes for its type

Stem cells
◦ Unspecialized cells
capable of differentiating
into any cell type
DNA, genes, & chromosomes
OBJECTIVE 5
DNA, Genes, & Chromosomes
“Forms” of DNA
Chromosomes – DNA sequences that are
made of genes coding for protein
 Chromatin – condensed DNA (not visible)
 Chromatids – visible replicated
chromosomes during cell division

Genetic variation
OBJECTIVE 6
Variation comes from:

Meiosis/sexual
reproduction
◦ Crossing over,
random
fertilization

Errors in DNA
replication
◦ Substitution,
deletion, insertion

Environmental
factors