Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
105 Cards in this Set
- Front
- Back
|
What is the cell cycle? |
The sequence of stages through which a cell passes from one cell division to the next. |
|
|
What is Mitosis (M)? |
A type of cell division in which a daughter cell receives the same number of chromosomes as the parent cell. Occurs when the components of the cytoplasm and nucleus are divided to give rise to two identical daughter cells. |
|
|
What is cytokinesis? |
The division of cytoplasm. |
|
|
What is interphase? |
The time interval between nuclear divisions when a cell increases in mass, roughly doubles the cytoplasmic components, and duplicates chromosomes. |
|
|
What are the stages of interphase? |
G1 (gap 1), S (synthesis), and G2 (gap 2). Occasionally Gap 0 (gap not) when the cell is done growing/dividing. |
|
|
What occurs during gap 1? |
Rapid growth |
|
|
What occurs during synthesis? |
The duplication of chromosomes. |
|
|
What occurs during gap 2? |
Another period of growth and preparation for further division. |
|
|
What is chromatin? |
The complex of DNA and protein that make up chromosomes. |
|
|
What is the centromere? |
The structure that holds chromatids together. |
|
|
What are sister chromatids? |
A chromosome and it's duplicate, attatched to one another by a centromere until separated during mitosis. |
|
|
What does an unduplicated condensed chromosome look like? |
A noodle! |
|
|
What does a duplicated condensed chromosome look like? |
An x! |
|
|
What are the phases of mitosis? |
Prophase, metaphase, anaphase, and telophase. |
|
|
What happens during prophase? |
The chromosomes in the nucleus become visible as they shorten and thicken. (In animal cells) centrioles move to opposite poles of the cell and provide attatchment for the spindle fibres. The nuclear membrane dissolves. |
|
|
What are centrioles? |
Small protein bodies found in the cytoplasm of animal cells that provides attachment for spindle fibres during cell division. |
|
|
What are spindle fibres? |
Protein structures that guide chromosomes during cell division. |
|
|
What happens during metaphase? |
Chromosomes composed of sister chromatids move toward the centre of the cell to form the equatorial plate. |
|
|
What happens during anaphase? |
Centromeres divide and the siter chromatids move to opposite poles of the cell. |
|
|
What happens during telophase? |
The chromosomes reach the opposite poles of the cell and begin to lengthen. The spindle fibres dissolve and a nuclear membrane forms around each mass of chromatin. |
|
|
What determines a cell's ability to undergo mitosis? |
How specialized the cell is. |
|
|
Which two types of cells in the human body divide endlessly? |
Sperm-producing cells (spermatogonia), and the cells of a cancerous tumor. |
|
|
What are telomeres? |
The cap at the end of a chromosome. Each time a cell goes through the cell cycle and divides, the telomeres shorten. |
|
|
What is telomerase? |
An enzyme that effects the length of a telomere. |
|
|
What is meiosis? |
Two-stage cell division in which the chromosome number of the parental cell is reduced by half. |
|
|
What does haploid mean? |
The term refers to the number of chromosomes in a gamete (23). |
|
|
What does diploid mean? |
The term refers to twice the number of chromosomes in a gamete (46). |
|
|
What are homologous chromosomes? |
Paired chromosomes similar in shape, size, gene arrangement, and gene information. |
|
|
What is meiosis 1? |
Reduction division. Occurs when the diploid cell is reduced to the haploid cell. |
|
|
What is meiosis 2? |
The separation of the two chromatids produced by meiosis 1. |
|
|
What is a tetrad? |
A pair of homologous chromosomes, each with two chromatids. |
|
|
What is synapsis? |
The pairing of homologous chromosomes. |
|
|
What is "crossing over"? |
The exchange of genetic material between two homologous chromosomes. |
|
|
What is nondisjunction? |
The failure of a pair of homologous chromosomes to separate properly during meiosis. |
|
|
What is polyploidy? |
A condition in which an organism has more than two complete sets of chromosomes. |
|
|
What is a trisomy? |
The condition in which there are three homologous chromosomes in place of a homologous pair. |
|
|
What is a monosomy? |
The condition in which there is a single chromosome in place of a homologous pair. |
|
|
What is a karyotype chart? |
A picture of chromosomes arranged in homologous pairs. |
|
What is Down syndrome? |
Trisomy 21 |
|
What is turner's syndrome? |
Monosomy X. Characterized by a shorter stature, wider necks, a range of mental abilities, and sterility. |
|
What is kleinefelter's syndrome? |
Trisomy XXY. Characterized by a male with some female secondary sex characteristics, and sterility. |
|
|
What is "super male" syndrome? |
XYY |
|
What is Edward's syndrome? |
trisomy 18. Low survival rate. |
|
What is Patau's syndrome? |
Trisomy 13. low survival rate. |
|
|
What is complementary base pairing? |
Pairing of the nitrogenous base of one strand of DNA with the nitrogenous base of another strand. |
|
|
What does DNA consist of? |
Two strands of nucleotides |
|
|
What does each nucleotide contain? |
A deoxyribose sugar, a phosphate group, and a nitrogenous base. |
|
|
What does the structure of each DNA strand look like? |
It has a backbone of sugar and phosphate groups, and a nitrogenous base that sicks out from the backbone. |
|
|
What is a purine always paired with? |
A pyrimidine. |
|
|
Which bases are purines? |
Adenine and Guanine |
|
|
What bases are pyrimidines? |
Thymine, cytosine, and uracil. |
|
|
What holds the double helix of DNA together? |
The hydrogen bonds between the complementary bases. |
|
|
What does it mean to be antiparallel? |
Parallel but running in opposite directions; the 5' end of one strand of DNA aligns with the 3' end of the other strand in a double helix. |
|
|
What is at the 5' end of DNA? |
It has a carbon and phosphate group |
|
|
What is at the 3' end of DNA? |
A carbon and the hydroxyl group of the deoxyribose sugar. |
|
|
What is DNA replication? |
The process whereby DNA makes exact copies of itself. |
|
|
What is semiconservative replication? |
The process of replication in which each DNA molecule is composed of one parent strand and one newly synthesized strand. |
|
|
What is a "template"? |
A single-stranded DNA sequence that acts as the guiding pattern for producing a complementary DNA strand. |
|
|
What enzyme unwinds the DNA helix by breaking hydrogen bonds between the complementary bases? |
DNA Helicase |
|
|
What prevents bonds between bases from reforming during the separation of DNA strands? |
Proteins bind to the separated DNA strands and help hold them apart. |
|
|
What is the point at which the two template strands are separating called? |
The replication fork |
|
|
Describe the sequence of events that occur while DNA strands are being replicated.
|
-DNA helicase opens the double helix. -Proteins bind to the DNA to keep the two strands separate. -RNA primers are attached to the template strands. -DNA polymerase synthesizes the new DNA strands. The leading strand is synthesized continuously, and the lagging strand is synthesized in short fragments. DNA polymerase lll adds complementary nucleotides in the 5' to 3' direction, using single stranded primers as starting points. |
|
|
What is DNA polymerase lll? |
The enzyme that synthesizes complementary strands of DNA during DNA replication. |
|
|
What gives DNA polymerase III a starting point to begin synthesizing the new DNA strand? |
A single stranded ribonucleic acid, called a primer |
|
|
Which direction does DNA polymerase III add nucleotides? |
the 5' to 3' direction. |
|
|
What is the leading strand? |
The new strand of DNA that is synthesized towards the replication fork and continuously during DNA replication. |
|
|
What is the lagging strand? |
The new strand of DNA that is synthesized away from the replication fork and in short fragments, which are later joined together. |
|
|
What is DNA polymerase I? |
An enzyme that removes RNA primers and replaces them with the appropriate nucleotides during DNA replication. |
|
|
What is DNA ligase? |
An enzyme that joins DNA fragments together. |
|
|
What are the steps in creating the lagging strand? |
-DNA polymerase III adds nucleotides to the primers to form short fragments of DNA. -DNA polymerase I removes the RNA primers and replaces them with DNA nucleotides. A nick is left between fragments. -DNA ligase joins the fragments together. |
|
|
What is gene expression? |
The conversion of a gene into a specific trait through the production of a particular polypeptide. |
|
|
What is ribonucleic acid (RNA)? |
A nucleic acid consisting of nucleotides comprised of the sugar ribose and nitrogenous bases. |
|
|
What is transcription? |
The process of converting DNA into messenger RNA. |
|
|
What is messenger RNA (mRNA)? |
The product of transcription of a gene; mRNA is translated by ribosomes into protein. |
|
|
What is translation? |
The process of synthesizing a specific polypeptide as coded for by messenger RNA. |
|
|
What are the three main structural differences between RNA and DNA? |
-The sugar in RNA has an extra hydroxyl group and is called ribose instead of deoxyribose. -Instead of thymine, uracil is found in RNA. -RNA is single-stranded |
|
|
What are the three types of RNA needed to convert genes into proteins? |
messenger RNA (mRNA), transfer RNA (tRNA), and ribosomal RNA (rRNA). |
|
|
What are the two main stages of gene expression? |
Transcription and translation. |
|
|
What three processes is transcription divided into? |
Initiation, elongation, and termination. |
|
|
What is RNA polymerase? |
An enzyme that transcribes DNA. |
|
|
What is a promoter? |
A sequence of DNA that binds RNA polymerase in front of the gene. |
|
|
What is a template strand? |
The strand of DNA that the RNA polymerase uses as a guide to build complementary mRNA. |
|
|
What is a termination sequence? |
A sequence of bases at the end of a gene that signals the RNA polymerase to stop transcribing. |
|
|
Describe what occurs during transcription initiation. |
RNA polymerase binds to DNA at a promoter. DNA double helix is unwound exposing the template strand. |
|
|
Describe what occurs during transcription elongation. |
mRNA is synthesized by RNA polymerase using one strand of DNA as a template. DNA that has already been transcribed rewinds into a double helix. |
|
|
Describe what occurs during transcription termination. |
Transcription stops once a termination sequence is reached by RNA polymerase. mRNA and RNA polymerase are released. |
|
|
What is a codon? |
A sequence of three bases in DNA or complementary mRNA that serves as a code for a particular amino acid. |
|
|
What is a start codon? |
Specific codon (AUG) tha signals the start of translation. Produces methionine. |
|
|
What is a stop codon? |
A specific codon that signals the end of translation. |
|
|
What is a ribosome? |
An organelle composed of RNA and protein and located in the cytoplasm that carries out protein synthesis. |
|
|
Describe what happens during translation initiation. |
A ribosome recognizes a specific sequence on the mRNA and binds to that site. It moves along in the 5' to 3' direction, adding a new amino acid to the growing polypeptide chain each time it reads a codon. |
|
|
What are ribosomes made up of? |
A large subunit and a small subunit |
|
|
What is transfer RNA (tRNA)? |
The form of RNA that delivers amino acids to a ribosome during translation. |
|
|
What is an anticodon? |
A group of three complementary bases on tRNA that recognizes and pairs with a codon on the mRNA. |
|
|
Describe what occurs during translation elongation. |
A start codon is recognized. The tRNA with the anticodon complementary to the start codon enters the P site. The next tRNA carrying the required amino acid enters the A site. A peptide bond forms between the first and second amino acid. The ribosome shifts over one codon so that the second tRNA is now in the P site, and allows a third tRNA into the A site. Used tRNAs are released by the E site. |
|
|
What are point mutations? |
A mutation at a specific base pair. |
|
|
What are gene mutations? |
A mutation that changes the coding for amino acids. |
|
|
What are silent mutations? |
Mutations that does not result in a change in the amino acid coded for. |
|
|
What is a missense mutation? |
A mutation that results in a single substitution of one amino acid in the polypeptide. |
|
|
What is a nonsense mutation? |
A mutation that converts a codon for an amino acid into a stop codon. |
|
|
What is deletion? |
The elimination of a base pair or group of base pairs from a DNA sequence. |
|
|
What is insertion? |
The placement of an extra nucleotide in a DNA sequence. |
|
|
What is a framshift mutation? |
A mutation that causes the reading frame of codons to change (ie. deletion or insertion) |
|
|
What is translocation? |
The transfer of a fragment of DNA from one site in the genome to another location. Usually occurs between nonhomologous chromosomes. |
|
|
What is inversion? |
The reversal of a segment of DNA within a chromosome. |
