Explain the structure and function of the cell nucleus. Include the terms nuclear envelope, nucleoli, chromatin, chromosomes, autosomes, and sex chromosomes
What will be an ideal response?
The largest organelle is the nucleus. It is enclosed by a double membrane called the nuclear envelope. Within the nucleus, dense regions known as nucleoli synthesize ribosomes. Dark strands of chromatin are seen throughout the nucleus. As a cell prepares to divide, the chromatin condenses to form the chromosomes. In humans, there are 23 pairs of chromosomes (46 chromosomes) in most cells Certain cells, such as sperm and eggs, carry only one copy of each chromosome and have 23 unpaired chromosomes. Human males have one pair of chromosomes that are not completely matched. Members of this pair are known as sex chromosomes. There are two types of human sex chromosomes: X and Y. Males carry an X chromosome and a Y chromosome, and females carry two X chromosomes. All other chromosomes are known as autosomes.
You might also like to view...
Transgenic animals made by pronuclear injection can be limited for studies of the links between genes and disease because
A) the transgene allele must be dominant to the normal, endogenous allele and some diseases are caused by recessive mutations. B) the transgene allele must be recessive to the normal, endogenous allele and some diseases are caused by dominant mutations. C) all diseases are caused by mutations in multiple genes. D) diseases are not caused by specific alleles of a gene, but by posttranslational modifications of proteins.
Gene S controls the sharpness of spines in a type of cactus. Cactuses with the dominant allele, S, have sharp spines, whereas homozygous recessive ss cactuses have dull spines. At the same time, a second gene, N, determines whether or not cactuses have spines. Homozygous recessive nn cactuses have no spines at all. The relationship between genes S and N is an example of _____.
A) incomplete dominance B) epistasis C) pleiotropy D) codominance
Trees with needle-shaped leaves and a thick cuticle with stomata sunk below the leaf surface dominate ____________________.
Fill in the blank(s) with the appropriate word(s).
Evolution of the globin gene family has been characterized by
a. duplication and divergence of genes. b. fusion of exons. c. duplication of gene clusters. d. mutations creating pseudogenes. e. All of the above.