Translocation Down syndrome is a type of Down syndrome that is caused when one chromosome breaks off and attaches to another chromosome. In this case, there are three 21 chromosomes but one of the 21 chromosomes is attached to another chromosome.
When part of a chromosome breaks off and attaches to a nonhomologous chromosome?
If a chromosome break occurs in each of two nonhomologous chromosomes and the two breaks rejoin in a new arrangement, the new segment is called a translocation.
Which change to the chromosome causes Robertsonian translocation part of the chromosome breaks off causing missing genes on the chromosome?
A Robertsonian translocation results when the long arms of two acrocentric chromosomes fuse at the centromere and the two short arms are lost. If, for example, the long arms of chromosomes 13 and 14 fuse, no significant genetic material is lost—and the person is completely normal in spite of the translocation.
What are 4 types of chromosomal mutation?
Chromosome structure mutations can be one of four types:
- deletion is where a section of a chromosome is removed.
- translocation is where a section of a chromosome is added to another chromosome that is not its homologous partner.
- inversion is where a section of a chromosome is reversed.
What kinds of problems are caused by chromosomal abnormalities?
Chromosomal abnormalities can have many different effects, depending on the specific abnormality. For example, an extra copy of chromosome 21 causes Down syndrome (trisomy 21). Chromosomal abnormalities can also cause miscarriage, disease, or problems in growth or development.
What causes a deletion mutation?
A deletion mutation occurs when a wrinkle forms on the DNA template strand and subsequently causes a nucleotide to be omitted from the replicated strand (Figure 3). Figure 3: In a deletion mutation, a wrinkle forms on the DNA template strand, which causes a nucleotide to be omitted from the replicated strand.
Where do chromosomal abnormalities occur?
Structural chromosome abnormalities occur when part of a chromosome is missing, a part of a chromosome is extra, or a part has switched places with another part. Ultimately, this leads to having too much or too little genetic material. This is a cause of some birth defects. Each chromosome has many segments.
What affects the DNA sequence of an entire chromosome?
Some mutations affect a single gene, while others affect an entire chromosome. In biology a mutation means a change in an organism’s DNA. A muta- tion can happen during replication and affect a single gene. A mutation can also happen during meiosis and affect a whole chromosome.
Which of the following occurs when a piece of chromosome 14 breaks off and attaches to chromosome 21?
In translocation Down syndrome, the extra 21 chromosome may be attached to the 14 chromosome, or to other chromosome numbers like 13, 15, or 22. In some cases, two 21 chromosomes can be attached to each other. A small number of babies born with Down syndrome have translocation Down syndrome.