What is a Chromosome? Flashcards
Chromosome
In the nucleus of each cell, the DNA molecule is packaged into thread-like structures
called chromosomes. Each chromosome is made up of DNA tightly coiled many times
around proteins called histones that support its structure.
When are chromosomes visible under a microscope?
when the DNA that makes up chromosomes becomes more tightly packed during cell division
centromere
Each chromosome has a constriction point called the centromere, which divides the
chromosome into two sections, or “arms.”
The short arm of the chromosome
P
The long arm of the chromosome
Q
location of the centromere on each chromosome
gives the chromosome its characteristic shape, and
can be used to help describe the location of specific genes
What are DNA and histone proteins packaged into?
Chromosomes
How many chromosomes do people have?
In humans, each cell normally contains 23 pairs of chromosomes, for a total of 46.
Twenty-two of these pairs, called autosomes, look the same in both males and females
Which pair of chromosomes differs between male vs female?
The 23rd pair, the sex chromosomes, differ between males and females. Females have
two copies of the X chromosome, while males have one X and one Y chromosome
A normal male karyotype
with 22 autosomes, one X chromosome, and one Y chromosome
22 autosomes are numbered by
size
e human chromosomes lined up in pairs is
called
a karyotype
