genes Flashcards
A functional
hereditary unit made up
of DNA that occupies a
fixed location on a
chromosome.
Gene
Humans have
approximately ____________ proein-encoding
genes
20,000 -25,000
four biochemicals known as bases or nucleotides:
adenine (A), cytosine (C), guanine (G), and thymine (T)
it is entire set of DNA instructions found in a
cell.
Genome
In humans, the genome consists of ___ pairs
of chromosomes
23
The genetic composition of an
individual organism
Genotype
The observable appearance of
an individual organism.
Phenotype
The translation of the
genotype into the
phenotype of an
organism.
Gene Expression
An _____ is one of two or more
versions of DNA sequence (a single
base or a segment of bases) at a
given genomic location.
allele
- Having two identical alleles for a
given gene.
Homozygous
- Having two different alleles for a
given gene.
Heterozygous
- A gene that will produce its
characteristic phenotype only when it occurs in
a homozygous pair.
Recessive allele
-A gene that produces its
phenotype regardless of whether it occurs in a
heterozygous or homozygous pair.
Dominant allele
It is a type of cell division in sexually
reproducing organisms that reduces the number
of chromosomes in gametes (the sex cells, or egg
and sperm).
Meiosis
Crossing over is a cellular
process that happens during meiosis when
chromosomes of the same type are lined up.
Crossing over
are changes in the genetic
sequence, and they are a main cause of
diversity among organisms.
Mutations
Phenotypical characteristics that result
from expression of genes on the X
chromosome that are not duplicated on
the Y chromosome.
Sex-linked characteristic
The process by which one X chromosome
in each female cell is silenced to equalize
the amount of proteins produced by
males and females.
X chromosome inactivation
Variations that occur in a gene when a single base is
changed from one allele to the next
SINGLE NUCLEOTIDE POLYMORPHISMS (SNPS)
Variations in the number of sequences in a gene
compared to a reference genome
Copy-Number Variations (CNVs)
_______describes how much variation in a trait
observed in a population is due to genetic differences
heritability
refers to the development of potentially
heritable traits due to changes in gene
expression that do not involve changes in
DNA sequences.
Epigenetics
Three important processes that produce
lasting but reversible changes in gene
expression are __________
histone modification, DNA
methylation, and gene silencing by
non-coding RNA
Changes in the structure of histones that
make it more or less likely that a segment
of DNA will be transcribed.
Histone modification
Addition of a methyl group to a DNA
molecule turns off the gene.
DNA methylation
Regulation of gene expression by
segments of RNA that are not translated
into protein.
Gene silencing by non-coding RNA
