chromosomes test 2 material Flashcards
At the center of almost all cells is a ball-shaped structure called the ___________.
nucleus
how many chromosomes are inside a nucleus
46
A ___________ is a very long DNA molecule and associated proteins, that carry portions of hereditary information of an organism.
chromosome
if 1 dna strand was stretched out it would be how long
6ft long
___________ is a combination of 4 possible amino acids, bound in pairs, in a double helix structure.
DNA
what is half of a chromosome pair called
chromatid
what is the connecting point of chromosome pairs
centromere
ends of each chromosome is called a
telomere
A ___________ can be defined as a
region of DNA that controls
a hereditary characteristic.
gene
Humans have two types of chromosomes:
* Sex chromosomes- X chromosome (female), Y
chromosome (male). Sex chromosomes are
heterologous (different).
* Autosomes- non-sex chromosomes that is an
ordinarily paired type of chromosome that is the
same in both sexes of a species. Autosomes are
homologous (same).
- Gene- a region of DNA that
controls a hereditary
characteristic. - Alleles- alternate forms of the
same gene that can occupy the
same location on a chromosome. - Genotype- the pair of alleles a
person has. - Of all the forms (or alleles) a
gene has, each person inherits
only two of them — one from
the mother and one from the
father. - Locus- the location the similar
alleles occupy on a homologous
chromosome
what is genotype
- is an organism’s
full hereditary
information. - The genes that
we have.
what is phenotype
- is an organism’s
actual observed
properties, such
as appearance,
development, or
behavior. - The trait those
genes give us
Several factors are involved in determining patterns of inheritance, including where the trait-causing gene is located (on the autosomes or sex chromosomes) and whether one or two copies are
necessary for a given trait to be expressed.
hereditary
2 types of alleles
homozygous and heterozygous
difference between homozygous and heterozygous
homozygous has same alleles and heterozygous does not
heterozygous has one dominant and one recessive allele
____________________ inheritance is caused by a mutation in a gene located on an autosomal chromosome and occurs when one autosomal allele suppresses the expression of another allele.
Autosomal dominant
A ____________ gene from just one parent will result in the phenotype, which may be eye or hair color or may be a serious condition such as Huntington’s Disease.
dominant
- Autosomal dominant
means you only need to get
the abnormal gene from
one parent in order for you
to inherit the disease. One
of the parents may often
have the disease. - If just one parent has a
dominant gene defect,
EACH child has a __________
chance of inheriting the
disorder.
50%
Autosomal recessive inheritance also is caused by a mutation in a gene located on an autosome, but in this case, ________ copies of the recessive gene are needed for the trait to be expressed.
two
what are some autosomal recessive conditions?
Cystic fibrosis and diseases affecting metabolism
(such as phenylketonuria or PKU) are autosomal
recessive conditions.
- If a person only has one defective gene in the pair, they are considered a ________. This means they can still pass the abnormal gene to their children.
carrier
____________ is a genetic condition where a person has more than one genetically distinct set of cells
Mosaicism
Most chromosome
abnormalities occur when?
as an accident in the egg
or sperm. Therefore,
the abnormality will be
present in every cell of
the fetus.
Structural anomalies
A portion of the
chromosome is missing or deleted.
deletion
Structural anomalies
A portion of the
chromosome is duplicated,
resulting in extra genetic material.
- Duplications:
Structural anomalies
When a portion of
one chromosome is transferred to
another chromosome.
- Translocations:
Structural anomalies
A portion of the
chromosome has broken off,
turned upside down and
reattached, therefore the genetic
material is inverted.
- Inversions:
Structural anomalies
A portion of a chromosome
has broken off and formed a circle
or ring. This can happen with or
without loss of genetic material
Structural Abnormalities
- Rings:
what is Aneuploidy?
incorrect chromosome number
common ones are trisomy 13, 18, 21
____________ is the loss of one chromosome in cells, is another kind of aneuploidy.
Monosomy
- People with monosomy have one copy of a
particular chromosome in cells instead of the normal two copies. - A women with Turner syndrome usually have only one copy of the X chromosome
Factors That Can Increase the Risk
of Chromosome Abnormalities
maternal age
environment
