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Flashcards in Chapter 3 Deck (46)
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1
Q

proteins

A

three-dimensional molecules that serve a wide variety of functions through their ability to bind to other molecules

2
Q

nucleus

A

organelle found in all eukaryotic cells, contains DNA, RNA, and other things

3
Q

molecules

A

structures made up of two or more atoms; can combine with other molecules to form more complex structures

4
Q

DNA

A

double-stranded molecule that contains the genetic code; a main component of chromosomes

5
Q

RNA

A

single-stranded molecule similar in structure to DNA; three forms essential to protein synthesis: messenger RNA (mRNA), transfer RNA (tRNA), and ribosomal RNA (rRNA)

6
Q

cytoplasm

A

semifluid, gel-like substance contained within the cell membrane; nucleus and numerous structures involved w/ cell function found in cytoplasm

7
Q

protein synthesis

A

manufacture of proteins; assembly of chains of amino acids into functional protein molecules; directed by DNA

8
Q

mitochondria

A

structures contained within the cytoplasm of eukaryotic cells that convert energy, derived from nutrients, to a form that can be used by the cell

9
Q

ribosomes

A

structures composed of a form of RNA called ribosomal RNA (rRNA) and protein; found in a cell’s cytoplasm and are essential to the manufacture of proteins

10
Q

mitochondrial DNA (mtDNA)

A

DNA found in the mitochondria; inherited only from the mother

11
Q

somatic cells

A

all the cells in the body except those involved in reproduction

12
Q

gametes

A

sex cells (eggs and sperm); developed from precursor cells in ovaries and testes

13
Q

zygote

A

cell formed by the union of an egg cell and sperm cell; contains the full complement of chromosomes (46 in humans); has the potential of developing into an entire organism

14
Q

nucleotides

A

basic units of the DNA molecule, composed of a sugar, a phosphate, and 1 of 4 DNA bases

15
Q

replicate

A

to duplicate; the DNA molecule is able to make copies of itself

16
Q

enzymes

A

specialized proteins that initiate and direct chemical reactions in the body

17
Q

complementary

A

in genetics, referring to the fact that DNA bases form pairs (base pairs) in a precise manner; ex: adenine only bonds to thymine (these are complementary because one requires the other to form a complete DNA pair)

18
Q

hemoglobin

A

a protein molecule that occurs in red blood cells and binds to oxygen molecules

19
Q

hormones

A

substances (usually proteins) that are produced by specialized cells and that travel to other parts of the body, where they influence chemical reactions and regulate various cellular functions

20
Q

amino acids

A

small molecules that are the components of proteins

21
Q

messenger RNA (mRNA)

A

form of RNA that’s assembled on a sequence of DNA bases; carries the DNA code to the ribosome during protein synthesis

22
Q

codons

A

triplets of messenger RNA bases that code for specific amino acids during protein synthesis

23
Q

transfer RNA (tRNA)

A

type of RNA that binds to specific amino acids and transports them to the ribosome during protein synthesis

24
Q

mutation

A

a change in DNA; the term can refer to changes in DNA bases (specifically called point mutations) as well as to changes in chromosome number and/or structure

25
Q

gene

A

sequence of DNA bases that specifies the order of amino acids in an entire protein, a portion of a protein, or any functional product, such as RNA; a gene may be composed of thousands of DNA bases

26
Q

genome

A

the entire genetic makeup of an individual or species; in humans, it’s estimated that the human genome comprises about 3 billion DNA bases

27
Q

noncoding DNA

A

DNA that does not direct the production of proteins; however such DNA segments produce thousand of molecules (ex: RNA) that are involved in gene regulation; thus the term noncoding is misleading

28
Q

exons

A

segments of genes that are transcribed and are involved in protein synthesis (prefix “ex” = expressed)

29
Q

introns

A

segments of genes that are initially transcribed and then deleted; not expressed, and aren’t involved in protein synthesis

30
Q

regulatory genes

A

genes that influence the activity of other genes; direct embryonic development and are involved in physiological processes throughout life; critically important to the evolutionary process

31
Q

homeobox genes

A

evolutionarily ancient family of regulatory genes that directs the development of the overall body plan and the segmentation of body tissues; there are at least 20 families of homeobox genes

32
Q

sickle-cell anemia

A

severe inherited hemoglobin disorder in which red blood cells collapse when deprived of oxygen; results from inheriting two copies of a mutant allele; the type of mutation that produces the sickle-cell anemia allele is a point mutation

33
Q

point mutation

A

change in one of the four DNA bases

34
Q

chromosomes

A

discrete structures composed of DNA and proteins found only in the nuclei of cells; chromosomes are visible under magnification only during certain phases of cell division

35
Q

autosomes

A

all chromosomes except sex chromosomes

36
Q

sex chromosomes

A

in mammals, the X and Y chromosomes

37
Q

locus

A

position or location on a chromosome where a given gene occurs; the term is sometimes used interchangeably with gene

38
Q

alleles

A

alternate forms of a gene; occur at the same locus on paired chromosomes and thus govern the same trait, but because they’re different, their action may result in different expressions of that trait

39
Q

karyotype

A

chromosomes of an individual, or what is typical of a species, viewed microscopically and displayed in a photograph; chromosomes are arranged in pairs and according to size and position of the centromere

40
Q

mitosis

A

simple cell division; the process by which somatic cells divide to produce two identical daughter cells

41
Q

meiosis

A

cell division in specialized cells in ovaries and testes; meiosis involves two divisions and results in four daughter cells, each containing only half the original number of chromosomes; these cells can develop into gametes

42
Q

recombination

A

the exchange of genetic material between paired chromosomes during meiosis; also called “crossing over”

43
Q

clones

A

organisms that are genetically identical to another organism; term may also be used to refer to genetically identical DNA segments, molecules, or cells

44
Q

random assortment

A

chance distribution of chromosomes to daughter cells during meiosis; along with recombination, random assortment is an important source of genetic variation (but not new alleles)

45
Q

polymerase chain reaction (PCR)

A

method of producing thousands of copies of a DNA sample

46
Q

Human Genome Project

A

an international effort aimed at sequencing and mapping the entire human genome, completed in 2003