GENETICS UNIT Flashcards
Nucleus:
membrane bound control center of
cell containing X-shaped structures called
chromosomes. Each chromosome consists
of two chromatids held together by a
centromere.
Chromosome:
X-shaped structure
consisting of a single DNA molecule.
DNA Molecule:
consisting of genes, the
“code of life”
Organism:
½ genes mom + ½ genes dad
Interphase:
chromosomes can not be seen;
doubling of chromosomes; nuclear membrane
present; 99% of cell life.
Prophase:
spindle fibers form; chromosomes seen
(randomly arranged).
Metaphase:
chromosomes line up in the Middle,
no nuclear membrane.
Anaphase:
chromosomes move Apart (Away)
Telophase:
Two joined cells; two nuclear
membranes form
Cytokinesis:
Two separated daughter cells form.
Cell Division:
growth (embryo, fetus, infancy → adulthood) and
repair/maintanence of an organism
Asexual Reproduction (ex: bacteria, hydra, worms):
simple life
1 parent / 2 daughter cells
parent/daughter cells identical appearance
(genes)
parent/daughter
cell same number of
chromosomes
Sexual Reproduction (ex: animals, angiosperms)
Two parents (male, female)
daughter cells are a mixture/combination of
genes compared to parent cell (by crossover)
parent to daughter
cell different number
of chromosomes
Parent
2x chromosomes compared to
daughter cells
Daughter
half (½) chromosomes
compared to parent cell
Organism (offspring):
½ alleles mom; ½ alleles dad “stronger ”
Mixture of our parents
(our dominant traits are usually
shown; only if both parents have recessive alleles will trait
be shown)
Variety (variation)
allows the organism to be
better adapted to a changing environment.
Variation
provides choices for SURVIVAL !!
Cancer:
abnormal cell division; uncontrolled
mitosis; certain DNA mutations cause cells to
divide in an uncontrolled way.
CAUSE -
Mutations are caused by:
1] Chemicals (carcinogens; ex: smoking,
gasoline, alcohol, fried foods)
2] Radiation (high dose; atomic bomb, nuclear
reactor meltdown Chernobyl (for Simon),
Ukraine)
3] Hereditary (ex: breast cancer)
TREATMENT-
surgery, radiation, drugs,
immunotherapy.
PREVENTION-
avoid smoking, eat healthy diet,
protect skin from bright sunlight. Vitamins may
help.
Gene =
allele (dad) + allele (mom)
Allele
(part of gene) = T or t
Purebred (homozygous)=
same alleles (gene);
TT, tt
Hybrid (heterozygous)=
mixture of alleles; Tt
Dominant =
shows itself (strong); Tt, TT
Recessive =
often hidden (weak); tt
Offspring =
children
Punnett Squares:
is a technique used to predict what
percentage of offspring (children) will be likely to
have a particular trait (physical feature).
Trait:
physical (behavioral) feature of organism
Gene =
allele (dad) + allele (mom)
Allele (part of gene) =
T or t
Hybrid (heterozygous)=
mixture of alleles (gene); Tt
Purebred (homozygous)=
same alleles (gene); TT, tt
Dominant =
capital and shows itself (strong); Tt, TT
Recessive =
lowercase and often hidden (weak)
except when all alleles (genes) are recessive; tt
Offspring =
children
Genotype =
the genetic makeup of an organism
Ex: TT, Tt, tt
Phenotype =
the physical observable appearance of
an organism. Ex: tall, short
Trait:
physical feature on an organism
Origin of organism’s trait =
½ Mom & ½ Dad
Phenotype:
all traits;
Mixture
of our parents (our dominant traits are
usually shown; only if both parents have recessive alleles
will trait be shown)
Asexual Reproduction (ex: bacteria, worms):
1 parent / 2 daughter cells
parent / daughter cells identical
appearance(genes)
parent / daughter cell same number of
chromosomes
Cell Division:
growth (embryo, fetus, infancy → adulthood) and
repair/maintanence of an organism
Sex chromosome =
23rd chromosome pair
Sex chromosome determines:
1] male/female
2] normal vs. red-green colorblind vision
3] with/ without hemophilia
4] muscular dystrophy other traits (sex-linked)
Sex-Linked Genes:
genes carried on sex
chromosomes; example red-green colorblindness
Carrier:
a person who does not show the observable trait but is
carrying the hidden recessive allele on the sex chromosome.
Cystic Fibrosis:
mucus in lungs & intestines;
mutation (deletion) of 3 base pairs.
Sickle-Cell Anemia:
sickle shape red blood cells
which can not carry much oxygen; co-dominant
allele.
Hemophilia:
slow or no blood clotting; recessive
allele (sex-linked disorder).
Down Syndrome:
extra copy of chromosome 21
causing a form of mental retardation;
Normal 21: II-shaped (2 chromatids)
Down Syndrome 21: III-shaped (3 chromatids)
