life science exam Flashcards
cell theory
- all cells come from pre-existing cells
- cells are the basic unit of life
- all organisms are composed of one or more cells
prokaryote only
- no nucleus
- plasmids
- no membrane-bound organells
eukaryote only
- has a nucleus
- - contains membrane-bound organells
both prokaryote and eukaryote
- contain DNA
- contain ribosomes
- cytoplasm
- cell membrane
cell wall
protects the cell –> plant only
large vacuole
stores water, nutrients, and waste –> plant only
chloroplast
site of photosynthesis –> plant only
nucleus
controls cell activity and contains DNA
smooth ER
produces lipids
rough ER
transports proteins, protein synthesis
ribosomes
protein synthesis
mitochondria
produces ATP, cellular respiration (the squiggly one)
golgi apparatus
stores, modifies, and transports protiens
cell membrane
allows for certain substances to enter and exit the cell
cytoplasm
provides structure and holds organelles in place
lysosome
digests and recycles waste –> plant only
DNA
deoxyribonucleic acid: chemical component found in the nucleus that stores coded instructions. Has the code for different proteins and cells
structure of DNA
DNA is a double helix and is said to be anti-parallel. Held together by hydrogen bonds between base pairs
nucleotides
the basic structure of DNA
- deoxyribose sugar (the pentagon)
- phosphate (the small circle, LINK phosphate cycle)
- nitrogenous bases (rectangle)
chromosome
a thread like strand of DNA that is encoded with genes. humans have 46 chromosomes in each cell (23 pairs)
homologous chromosomes
similar in length, centromere position, banding pattern. one is inherited from mother, and one from father
karyotype
a picture of homologous chromosomes arranged from largest to smallest
down syndrome
three chromosomes at number 21
turners syndrome
only one sex chromosome
kleinfelters syndrome
three sex chromosomes
gene
a section of DNA containing instructions and codes which produce specific proteins
RNA
ribonucleic acid
characteristics of RNA
- single stranded
- contains uracil (U)
- ribose sugar
characteristics of DNA
- double-stranded
- contains thymine (T)
- deoxyribose sugar
transcription
occurs in the nucleus
- DNA unwinds to expose bases
- Free mRNA strands bind following complimentary base pairing rules
- mRNA strand is produced
translation
occurs in the cytoplasm
- mRNA attaches to a ribosome in the cytoplasm
- tRNA brings specific amino acids to the ribosome
- amino acids are joined together via a peptide bond and a protein is formed.
importance of the cell cycle
important for growth, repair, development, maintenance of cells
mitosis
1 cell division, 2 daughter cells, one parent cell, 46 chromosomes, diploid, somatic (body) cell, genetically identical
meiosis
2 cell divisions, 1 parent cell, 4 daughter cells, 23 chromosomes, haploid, gamete, genetically different
genotype
genetic makeup of an individual
phenotype
physical expression of a geneotype within an environment
apoptosis
programmed cell death
interphase
DNA replicates, chromosomes are not visible, longest stage of the cell cycle
prophase
chromosomes condense, spindle fibres form, nuclear membrane breaks down
metaphase
chromosomes line up along the midline of the cell
anaphase
sister chromatids separate to opposite ends of the cell
telophase
new nuclear membrane forms, spindle fibres disappear, chromosomes decondense
cytokinesis
division of cytoplasm into 2 genetically identical daughter cells.
allele
different versions of the same gene
homozygous
two of the same alleles of a gene eg bb or BB