year 10 biology Flashcards
(31 cards)
what is DNA
a complex biomolecule that is found in nearly all living things. It carries genetic information inherited from ancestors.
- located in the nucleus
how does DNA relate to structure and function of an organism
DNA codes for proteins, determining an organism’s physical makeup and functions.
Structure of DNA
- double helix
- sugar and phosphate backbone
- nitrogenous bases in rungs
name the four nitrogenous bases
adenine - thymine
cytosine - guanine
(in complimentary base pairs, held together by hydrogen bonds)
identify the role of genes
genes provide information on the building of specific proteins. they do this through codons, which code for amino acids, forming proteins.
what is a codon
a group of three nitrogenous bases in a genetic sequence that codes for an amino acid, creating a specific proteins
- is found in mRNA or DNA
what is an anti-codon
a group of three nitrogenous bases that are complimentary to codons. they carry amino acids to the right spot, where they create proteins
what is an amino acid
a small molecule that joins with others to form proteins
what is a protein
a string of amino acids held together by a peptide bond
what is a gene and how does it relate to DNA molecules
genes are a segment of DNA that contain instructions for making proteins
what is cell division
the splitting of a cell to form new cells
what is mitosis
the cell division of somatic (body) cells for growth and repair
why is cell division for growth and repair important
- allows organisms to grow
- allows organisms to heal by replacing dead or damaged body cells
- helps maintain healthy tissues and organs
identify the stages of the cell cycle (and their approximate percentages)
interphase (90%), mitosis (10%) - prophase, metaphase, anaphase, telophase and cytokinesis (2%)
what happens in interphase
- Cell grows, performs normal functions
- DNA is replicated in preparation for division
- Organelles are duplicated
what happens in prophase
- Chromosomes condense and become visible
- Nuclear envelope breaks down
- Spindle fibers begin to form
what happens in metaphase
- Chromosomes line up along the cell’s equator
- Spindle fibers attach to centromeres
what happens in anaphase
Sister chromatids are pulled apart to opposite poles
what happens in telophase
- Chromatids arrive at poles and begin to uncoil
- New nuclear envelopes form around each set of chromosomes
what happens in cytokinesis
- The cytoplasm divides
- Two identical daughter cells are formed
how are sex cells different from other cells in the body
- sex cells combine during fertilization in sexual reproduction.
- Each sex cell carries half the number of chromosomes (23) (haploid).
- Fertilization forms a zygote with a full set of chromosomes (46) (diploid).
- each sex cell is genetically unique from parents or other daughter cells
identify the stages of meiosis
Interphase, Prophase I, Metaphase I, Anaphase I, Telophase I, Cytokinesis, Prophase II, Metaphase II, Anaphase II, Telophase II, and a final Cytokinesis.
(Interphase + PMAT(1) + Cyto + PMAT(2) + cyto)
how are sex cells produced by meiosis
in meiosis, a single diploid cell divides twice to form four haploid cells, each with half the number of chromosomes (23), ensuring genetic diversity and preparation for sexual reproduction.
what is an allele
a version of a gene
