Bio 101 Exam 2

study guides E,F,G

what is DNA?

a nucleic acid that carries genetic information and information necessary for the cell to make proteins.

What is the monomer (building block) of DNA?

nucleotides

What is each monomer of DNA made of?

deoxyribose (a sugar), phosphate group, and nitrogenous base.

In 1953, what two scientists discovered the structure of DNA

James Watson and Francis Crick (honorable mention - Rosalind Franklin for her X-ray diffraction images that contributed to the discovery)

Is DNA a single or double helix?

Double helix (each strand is a polymer)

What are the 4 nitrogenous base pairs used in DNA?

Adenine, Thymine, Cytosine, Guanine.

what is a gene?

a sequence of DNA that encodes a specific protein/ RNA molecule and determines specific traits in an organism.

what is a chromosome?

a discrete package of DNA coiled around proteins that carries genetic information.

what is a genome?

all the genetic material in its cells.

What is the Central Dogma of Biology?

DNA is transcribed into RNA and then translated into proteins.

In eukaryotes, where is DNA located?

the nucleus

What is RNA?

a single stranded nucleic acid (polymer)

In RNA, what are the monomers made of?

Ribose (a sugar), phosphate group, and nitrogenous base

What are the four nitrogenous bases used in RNA?

Adenine, Cytosine, Guanine, and Uracil

What is protein synthesis?

when RNA makes a copy (transcript) of the DNA message and in the case of eukaryotes, leaves the nucleus. RNA takes the message to a ribosome where the RNA is “read” and translated into an amino acid.

What are the functions of DNA?

storage of genetic information, replication, gene expression.

What are the functions of RNA?

messenger RNA (mRNA), transfer RNA (tRNA), ribosomal RNA (rRNA)

What are the 3 differences between the structures of DNA and RNA?

the sugar molecule, DNA is double-stranded, and RNA is single-stranded, and the nitrogenous bases.

Where does protein synthesis take place?

ribosomes

what is the relationship between a gene and a protein?

genes encode proteins

What are mutations?

accidental changes to the genome

How are mutations helpful for evolution?

they change the allele frequency in a population (genetic diversity)

Are all mutations bad?

No, some may not cause a change at all, while others may alter the protein product causing diseases or cell death.

What are the 3 types of mutations?

substitution, insertion, or deletion

How is RNA “read”

“read” three nucleotides at a time (known as a codon) during the process of translation

What causes mutations?

spontaneous errors during DNA replication, exposure to harmful chemicals/radiation

What is a mutagen?

external agent that induces mutations (ultraviolet radiation in sunlight, x-rays, chemicals in tobacco and environment)

what are homeotic genes?

these genes control development and mutations in these sections of DNA have influenced animal evolution greatly.

what are two ways mutations may benefit an organism?

aiding in reproduction or immunity

what do single-celled organisms use cell division for?

asexual reproduction, producing genetically identical offspring

what do multicellular organisms use cell division for?

growth, repair of tissues, and sexual reproduction

What do sexual life cycles include?

meiosis, fertilization, and mitosis.

What is meiosis?

cell division that reduces the chromosome number in half, resulting in four daughter cells

What is fertilization?

union of the sperm and the egg cell

what is mitosis?

divided genetic information into two identical nuclei

What is another name for programmed cell death?

apoptosis

What occurs in the development of a multicellular organism?

cell division and programmed cell death

What are the steps of DNA replication?

1. 1.DNA unwinds and separates

2. 2.nucleotides are added to their complementary base pairs

3. 3.enzymes proofread, correct errors, and join the fragments of DNA

4. 4.results in two identical DNA molecules

What is DNA polymerase?

the main enzyme involved in building a new strand of DNA

Why is ATP needed for DNA replication?

because nucleotide monomers are coming together to form a very high potential energy and organized, DNA polymer.

Why does DNA replication occur?

so, the new cell receives an exact copy of the genetic material during cell division

What happens if the enzymes don’t catch an error during DNA replication?

mutations

What repair or maintenance occurs in the cells of your body?

mitosis

what are the main events of the cell cycle for actively dividing cells?

interphase, mitosis, and cytokinesis

what happens during interphase?

cell prepares for division; consists of 3 stages G1 (cell growth and normal functions), S (DNA replication), and G2 (preparation for mitosis) - cell is at rest

what happens during mitosis?

contents of nucleus divide

What happens during cytokinesis?

cell splits into two daughter cells

which stage does a cell spend most of its life?

interphase

what are the results of mitotic cell division?

two daughter cells

What is the function of mitosis?

development, growth, repair, and cell replacement in multicellular organisms

what type of cells would mitosis make, gamete or body?

Body

why do you think some scientists say that mitosis “maintains chromosome number”?

because each daughter nucleus has the same number of chromosomes as the original nucleus.

what happens if cell division and apoptosis go uncontrolled?

could lead to cancer

What causes cancer?

when a single cell gains a mutation that causes it to lose control of its cell cycle

How can someone get cancer?

the mutation for cancer may be inherited or acquired during a person’s life

what are the two forms of reproduction?

asexual and sexual

what processes are involved in asexual reproduction?

binary fission and mitosis

what are 5 organism groups that reproduce asexually?

bacteria, archaea, amoeba, fungi, and plants

what is a benefit to spending more energy in sexual reproduction?

genetic diversity in changing environments

What are diploid cells?

cells with 2 sets of chromosomes (2n)

what is a karyotype?

A size-ordered chart of all the chromosomes in a body cell

How many total chromosomes do humans have?

46 chromosomes, 23 pairs

what are autosomes?

chromosomes that are the same for both sexes

what are sex chromosomes?

determine whether the individual is female or male (2 X chromosomes= female, X+Y chromosomes= male)

What does it mean when a chromosome is homologous to one another?

same size and order of genes

how are each of the chromosomes within a homologous pair inherited?

a person inherits 1 allele per gene from each parent

what do homologous chromosomes have in common?

size, centromere position, sequence of genes, and pattern of light and dark-staining bands

Are homologous chromosomes genetically identical?

they are NOT identical, the homologs differ in the combination of alleles, or version, of the genes they carry

Why is it important to reduce the chromosome number when sexually reproducing?

so that the offspring does not end up with twice the number of chromosomes as the parent when the sperm fertilizes the egg

What is a haploid cell?

cells with only one set of chromosomes (n)

what are examples of haploid cells?

sperm and egg

what is another term for sex cells (sperm and egg)?

gametes

What is the purpose of fertilization?

brings 2 sex cells together and restores the chromosome number to have what each parent has

sexually reproducing organisms require what 2 types of nuclear division?

Mitosis (in germ cells and somatic cells) and meiosis (in germ cells only)

Are all mutations passed from parent to offspring?

only mutations that occur in gametes (sex cells) are inherited

What is an allele?

different form of the same gene

how many autosome pairs are in each human?

22

what is a zygote?

a fertilized egg

what are somatic cells?

cells that do not participate directly in reproduction

When does meiosis happen in the cell cycle?

interphase stage

what is the function of meiosis in animal cells?

gamete production for sexual reproduction

What type of cells would meiosis make?

germ cells/haploid

what happens in the process called crossing over?

homologous chromosomes align and stick together so closely that they exchange sections

In mitosis do homologous chromosomes pair up?

no

in meiosis do homologous chromosomes pair up?

yes

in mitosis, is the daughter cell identical to original cell?

yes (except mutations)

In meiosis, is the daughter cell identical to original cell?

no

what is the primary function of daughter cells in mitosis?

growth, repair, and asexual reproduction

what is the primary function of daughter cells in meiosis?

sexual reproduction

In mitosis, does it start and end with a diploid cell?

yes

In meiosis, does it start and end with a diploid cell?

It starts with a diploid cell, but ends with a haploid cell

if a human somatic, parent cell with 46 chromosomes divides through mitosis, is the daughter cell haploid or diploid?

diploid

In the testes, germ line cells divide through meiosis. the sperm cell of a horse that results from meiosis contains 32 chromosomes. How many chromosomes would you expect to find in a horse somatic cell?

64 chromosomes (32 × 2 = 64)

is a zygote haploid or diploid?

diploid

are gametes haploid or diploid?

haploid

What is a trait?

an inherited characteristic that corresponds to a protein

What is a locus?

the location of an allele on a chromosome

Who did the study of inheritance in pea plants?

Gregor Mendel

what is a dominant allele?

allele that encodes a protein regardless of what other allele was present

what is a recessive allele?

the allele that encoded a protein that was covered up or masked