Biology CP Midterm Review
Scale of Biology
LARGE -------------------------- SMALL
Biosphere
Ecosystem
Organism
Cell
DNA /Genes
DOMAINS of LIFE
Domain is BROADEST category- 3 domains
• ARCHAEA
Small, single celled, prokaryotic
• BACTERIA
• EUKARYA- more complex- eukayotic– 4 kingdoms
•
•
•
•
Protists
Fungi
Plants
Animals
– Invertebrates
– Vertebrates
Mammals
Characteristics of Eukaryotic Cells
• Membrane-bound
nucleus (contains DNA) nucleus
• Organelles in cytoplasm
organelles
• Larger, can be
multicellular
cell membrane
Eukaryotic Cells- Plants & Animals
ANIMAL cells
- No cell wall
- many small
vacuoles
PLANT cells
- Chloroplasts
- Cell wall
- 1 large vacuole
Characteristics of Prokaryotic Cells
• No nucleus or
organelles
nucleus
• DNA in cytoplasm
organelles
• Small, all are unicellular
cell membrane
Structure of Cell Membrane
cell membrane
carbohydrate
chain
cholesterol
protein
protein channel
• FLUID MOSAIC MODEL
protein
Osmosis- SALT SUCKS
• Movement of WATER across selectively
permeable membrane
Four groups of large Biomolecules
• Carbohydrates
– Sugar (mono/disaccharide), starch/fiber
(polysacch)
– Main source of body’s energy
• Lipids/fats/sterols
– Make up membranes, used for energy
• Proteins
– Structural building blocks, enzymes
• Nucleic Acids
– DNA/RNA, stores genetic ‘code’
Enzymes = proteins that speed up
specific reactions in cells
• Activation energy: “start up” energy to get a
chemical reaction started
• Catalyst: anything that speeds up chemical
reactions
• Enzyme: special protein – catalyst in organisms
– Ex: sucrase, amylase
– Anything with suffix -ase = enzyme
• Substrate: binds to the enzyme; must fit into active
site
– Ex: sucrose
• Active site: place (on enzyme) where the substrate
fits
Cell Cycle
I. Interphase (90% time)
1.) G1 phase- cell grows
2.) S phase- genetic material duplicates
3.) G2 phase- cell prepares to divide
• DNA loosely packed as chromatin
II. Mitosis (10%)
4.) M phase (mitotic)- mitosis (PMAT) and
cytokinesis
Diploid (2n) vs. Haploid (n) Cells
•Body Cells
•Sex Cells (egg and sperm)
•Contain both homologous
chromosomes
•Contain only one of the
homologous chromosomes
•Total = 46 chromosomes
•Total = 23 chromosomes
(44 autosomes & 2 sex)
• Reproduce through mitosis
(22 autosomes & 1 sex)
• Made through meiosis
Meiosis results in 4 haploid gamete cells
– Meiosis occurs in sex cells
– Involves 2 cell Divisions*
– Meiosis produces 4 gametes* which are
haploid (n) cells.
Parent Cell
2n
– Note: This picture
During interphase
2n
Does not show
Chromosome #’s.
Meiosis 1
n
n
4 haploid gametes
n
n
n
Meiosis 2
n
Mitosis vs. Meiosis
Mitosis and meiosis are types of nuclear division
that make different types of cells.
Mitosis occurs in body cells
Meiosis occurs in sex cells
Mitosis makes more diploid
(2n) cells
Meiosis produces gametes
(haploid (n) cells)
DNA is composed of four types of
nucleotides.
• DNA (polymer) is made up of a long chain of
nucleotides (monomer).
• Each nucleotide has three parts:
– phosphate group
phosphate group
nitrogenous
base
– Sugar (deoxyribose)
– Nitrogenous base
There are 4 different
types of nucleotides
deoxyribose (sugar)
Quick Review…
• GENE= unit of heritable information in DNA
(region with coding for a trait)
If nucleotides are the building blocks of
DNA/RNA, what are the building blocks of
PROTEINS??
• RNA vs. DNA…
– RNA has a ribose sugar.
– RNA has uracil instead of thymine.
– RNA is a single-stranded structure.
GENE ANIMATION
DNA
Replication
TRANSCRIPTION
DNA
RNA
TRANSLATION
PROTEINS
• REPLICATION: Exact copy of DNA is made
using each half as a template (in nucleus)
• TRANSCRIPTION: Converting DNA sequence
(gene) into a single stranded mRNA molecule (in
nucleus)
• TRANSLATION: Converting mRNA message
into a polypeptide/protein (in cytoplasm, done by
ribosomes)
Genetics Basics
1. ALLELE = alternative forms of a gene… ex. Brown
hair allele, black hair allele (gene is for hair color)
2. You have TWO alleles for each character- one
came from your mom, one from your dad
3. Each gamete carries ONE allele (in MEIOSIS, the
parent cell splits its genetic information in half… if
mom was Bb, each egg will get either B or b)
4. GENOTYPE = Ee (heterozygous) … determined by
genetic code/genes/DNA
PHENOTYPE= Red eared… physical expression,
based on PROTEINS
Dihybrid Cross- HOW TO
Step 1- Determine Genotype of parents
CCPP X ccPp
Step 2- Determine different combinations of
parent alleles (USE FOIL)
CCPP … F=CP or O=CP or I=CP or L=CP
ccPp … F=cP or O=cp or I=cP or L=cp
Step 3- Line pairs up along 4x4 P-square
Each offspring will have 4 letters, describe with
two words for phenotype!
Intermediate/Incomplete and
Codominance
• Keys to remember:
– Mixed offspring will be HETEROZYGOUS
– Both letters are capitalized
– Denote with superscripted letters (CW or LT etc)
• INTERMEDIATE/INCOMPLETE- Blend of
parent traits
CRCR (red) x CWCW (White) = CRCW (Pink)
• CODOMINANCE- Both traits show
CBCB (black) x CWCW (White) = CBCW (stripes)
Many genes may interact to produce one
trait.
• Polygenic traits =
produced by two or
more genes
• Ex.- Eye, skin color
• Wide range of
variation
Order of dominance:
brown > green > blue.
Sex-Linked Traits
• Gene located on sex chromosome, usually the X
… Eye color in fruit flies (Red = R, white=r)
• Females (XX) carry two copies of the gene, may
carry the trait, but not show it (XRXr), will have
white eyes ONLY if she has copies (XrXr)
• Males (XY) carry one copy (no other X to ‘hide’
it), so they will either HAVE IT (XrY ) or NOT
HAVE IT (XRY)
*Males only have to inherit ONE copy, whereas
females must inherit 2!*
Disorders as SEX-LINKED Traits
• Usually located on X chromosome
• More common in males… Colorblindness
NOTICE:
- No male carriers
- More common in
Males than females
Principle of
segregation
during gamete formation, a particular
allele for one character can be paired with
either allele of another character (useful
for dihybrid crosses, FOIL)
Principle of
independent
assortment
genes are located on chromosomes,
behavior (separation) of chromosomes
during meiosis and fertilization accounts
for inheritance patterns
the two alleles for a character segregate
(or separate) during meiosis, so each
gamete carries only one allele for each
character
Chromosome
theory of
inheritance
Disorders as DOMINANT Traits
• Fewer of these than Recessively inherited
disorders, typically HETEROZYGOUS
• Not so bad: polydactyly
• Not Hot: Achondroplasia, Huntington’s disease
LETHAL DOMINANT alleles- embryos that are
homozygous are typically miscarried (do not
survive)
*those with disorder are typically Heterozygous