Unit 2 Flashcards Preview

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Flashcards in Unit 2 Deck (48):
1

Gregor Mendel

Australian monk who worked with pea plants and was the founder of mendelian genetics

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Heredity

Passing off of traits from parents to offspring

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Genes

Factors that control traits, they are on chromosomes and contain DNA

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Alleles

Alternate forms of genes

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Principle of dominance

If the dominant and recessive gene are there, the dominant gene will always be shown

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Law of segregation

Offspring inherit traits from both parents

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Genotype

Combination of alleles, represented by letters (homozygous, heterozygous dominant or heterozygous recessive)

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Phenotype

What a trait looks like when expressed

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Test cross

Used to see if an organism is homozygous dominant or heterozygous. Involves crossing an unknown genotype with homozygous recessive, will determine unknown allele.

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Incomplete dominance

A blending of traits, represented with R and R'

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Co dominance

Both traits are expressed, with have one letter with two superscripts

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Multiple alleles

When a gene has more then one possible alleles for a given trait

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Sex linked inheritance

T.H. Morgan used fruit flies

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Pedigrees

Charts that track inheritance of a certain trait alone members of a family, birth order goes from left to right

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Affected male

Filled in rectangle

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Not affected male

Not filled in rectangle

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Affected female

Filled in circle

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Not affected female

Not filled in circle

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Mitosis

The process by which nuclear material is asexually divided in somatic cells (body cells). Parent cells and daughter cells all have 46 chromosomes which is the diploid number (full number)

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Interphase

Cell grows and prepares for cell division by duplication DNA

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Prophase

Doubles chromatin strands shorter and thicken to form chromosomes, nuclear membrane and nuclei disappear, centrioles split, one travels to each pole of the cell. Spindle fibres attach to centromere of each chromosome

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Metaphase

Spindle fibers pull chromosomes into a line across the middle of the cell

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Anaphase

Spindle fibers contract and shorten, pulling centromere apart. Each single stranded chromosome moves to an opposite pole of the cell

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Telophase

Spindle fibers disappear, nucleolus appears in each new nucleus. Single stranded chromosomes start to uncoil to form chromatic. Cytokinesis occurs

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Cytokinesis

Seperation of the cytoplasm and it's contents into equal parts

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Cytokinesis in animal cells

Cell membrane pinches in from edges and forms a cleavage furrow

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Cytokinesis in plant cells

Cell wall forms between two cells forming a cell plate

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Meiosis

Cell division in gametes (sex cells). Creates 4 haploid daughter cells which aren't identical to parents cells.

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Prophase 1

Chromosomes condense, crossing over can happen, tetrad forms

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Metaphase 1

Tetrads align at cell equator

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Anaphase 1

Homologous chromosomes separate and move to opposite poles

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Telophase 1

Homologous chromosomes begin to uncoil, division of cytoplasm occurs

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Prophase 2

Chromosomes condense and attach to spindle fibres at centromeres

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Metaphase 2

Chromosomes line up across equator

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Anaphase 2

Sister chromatids are pulled to opposite poles

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Telophase 2

4 haploid daughter cells are produced (gametes)

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Humans have...

46 chromosomes, 22 pairs are somatic and one pair of sex chromosomes

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Crossing over

Exchange of genetic material, resulting in rearrangement of genetic material in homologous chromosomes

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DNA

Deoxyribonucleic acid, consists of 5-carbon sugar, phosphate, 4 kinds of nitrogen bases (purines- adenine and guanine, pyrimidines- cytose and thymine). Stores all cell information and directs cell activity. 5% contains genes and the other 95% is useless.

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DNA structure

Two chains of sugar- phosphates running parallel, sides of molecules held together by pairs of nitrogen bases (A-T and G-C). Helix is formed when ladder is twisted, letter sequence on one strand determines sequence on adjacent strand.

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RNA

Carries messages from DNA (nucleus) to the rest of the cell.

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Autosomes

Non sex chromosomes

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Homologous chromosomes

Very similar pair but not identical, may contain different alleles

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Karyotype

The number and visual appearance of the chromosomes in the cell nuclei

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Synapsis

Pairing up of homologous chromosomes in prophase 1

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Gametogenesis

Production of sex cells

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Spermatogenesis

Production of sperm cells

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Oogenesis

Production of egg cells