bio unit 3 test review

gonna go cry now

asexual reproduction

-one parent, quickly provides large numbers of offspring
- no variations so all organisms are genetically identical (clones)
-cells preform mitosis and then divide into two cells. cells contain a full set of chromosomes (2n)

sexual reproduction

-two parents allow variation in offspring
-need to find mate, happens more slowly
-must use gametes
-gametes fertilization results in zygote

gametes

special reproductive cells (sex cells)
contain half the normal number of chromosomes
combines during fertilization to restore normal number of chromosomes
-results in a zygote
sperm and egg in animal
pollen and ovules in plants

mitosis (cell division)

used in all forms of asexual reproduction
unicellular use to reproduce
multicellular use to grow/repair damaged tissue
one division of a cell makes two identical diploid(2n) cells with sets of chromosomes in homologous pairs
part of the cell cycle

the cell cycle

1. interphase - when the cell grows, functions, and copies its dna
   G1 phase, S phase, then G2 phase

2. cell division - includes mitosis (equally divides the chromosomes) and cytokinesis (equally divides the cytoplasm)
   includes prophase, metaphase, anaphase, and telophase

cancer

• uncontrolled cell division

• caused by mutations in genes that control cell cycle

malignant tumor - cancer cell scan exit tumor, enter blood, and spreader to other parts of body (metastasis)

benign tumor is not cancerous

• mutations happen do to chance or exposure to cancer causing substances

meiosis (reduction division)

makes gametes
one cell divides twice producing 4 different haploid (n) cells
separates chromosome pairs so offspring get one chromosome of each pair from each parent
result: 4 daughter cells instead of 2 daughter cells like mitosis

binary fission

bacteria’s way of reproduction
copying the single chromosome and then simply diving into two cells

chromosomes

humans have 46 (22 homologous pairs + 1 pair sex chromosomes)

homologous chromosome pair

chromosomes with the same size and shape and types of genes
carry genes for the same traits

alles

the option for the gene/trait
EX: trait of color in cats is the genes, the alleles are options so black or gray
organisms have two alleles for each gene - one from each parent
if both alles for the gene are the same = homozygous (pure bred)
if different = heterozygous (hybrid)

traits

determined by how the alleles interact with each other in the cell

EX:

• dominant/recessive - dominant allele shown over recessive allele

• incomplete dominance - neither allele is dominant or appears

• codominance - both alleles are dominant and appear

• multiple alleles - three or more choices for the allele are found in a population

• sex-linked - the allele is located on the x chromosome

polygenic

two or more genes each with its own allele options controls one specific trait

sex chromosomes

females are XX
males are XY

• Y chromosome is smaller than X so does not have the same genes

• many genes on X chromosome do not have a partner gene

karyotype

visual representation that shows all 23 pairs of humans chromomsomes

genes

determines our traits
the environment can affect expression of genes (ex: temperature)
each gene codes for a making particular protein (ex:proteins)

punnett squares

can be used to predict the probability of inheriting a specific trait

chromosomes defects

• caused when a person inherits too many or too few chromosomes

• most are lethal

nondisjunction

chromosomes do not separate properly during meiosis when gametes are made

trisomy

one extra chromosome

monosomy

one missing chromosome

down syndrome

• not lethal

• caused by inheriting an extra chromosome 21

pedigree chart

diagram that traces the occurrence of a trait in a family

sex-linked + recessive

• males only need one allele on the X

• females must inherit recessive allele on both X chromosomes to show trait

carrier

an individual with one recessive allele and one dominant allele

• does not show trait

• may pass the recessive allele to the next generation

DNA

the molecule that makes up genes and chromosomes

structure: double helix, two strands of nucleotides, one strand on each side

• made of nucleotides containing sugar

• made of phosphate group and one of 4 nitrogen bases
  

4 nitrogen base

• adenine

• thymine

• cytosine

• guanine

base pair rule

a - t
c - g

a - u

dna replication

the structure of DNA allows it to replicate itself almost perfectly

• uses the base rule to replicate

• happens during interphase, BEFORE mitosis

protein synthesis

same thing as translation

making proteins, how genes control your body

codon

a sequence of three bases in DNA

• each represents on specific amino acid

• ribosomes assemble amino acids in the order as they are listed in DNA codons

• how your body functions depends on the order of bases in your genes

RNA

made of nucleotides

types of RNA:

• mRNA - messenger RNA, copy DNA code for one gene

• tRNA - transfer RNA, carry amino acids to ribosomes

• rRNA - ribosomal RNA, form structure of ribosomes

transcription

• mRNA copies the DNA code from the gene in the nucleus

translation

• tRNA brings the correct amino acids to the ribosomes by matching bases with mRNA codons

mutagenic agents

any environmental factor that causes mutations

EX:

• radiations

• toxic chemicals

• carcinogens

• viruses

gene mutations

causes a change in DNA bases of a gene, which can change the shape of a proteins, which can change how a protein functions

• happens when DNA bases are altered (substitution, insertion, deletion)

• changes the codon which makes the wrong protein

• can only be passed to offspring if the mutation happens in reproductive cells (sperm or eggs)

damaged chromosomes

chromosomes that break

• duplication - section of chromosomes repeated

• deletion - section of chromosome missing

• inversion - section of chromosome is backwards

• translocation - section of chromosomes Is moved to different chromosomes

cystic fibrosis

• produced thick sticky mucus

• clogs lungs, difficultly breathing, more infections

• common in white europeans

tay sachs

• liquid build-up destroys nerve cells in brain and spinal cord

• result is death within 1-5 years usually

• common in eastern european jewish, french canadian

sickle cell anemia

• defective hemoglobin in red blood cells cause sickle cell shape

• can’t carry oxygen + cells clump together

• common in african americans/western mediterranian

cancer genes

oncogenes - mutations in genes that control cell cycle (mitosis)

• cells divide out of control

• happens in body cells, not gametes

• less than 5% cancers are inherited

polymerase

enzyme proofreads so base pairs are correct